JP4822535B2 - Liquid crystal display device and terminal device using the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a liquid crystal display device and a terminal device, and more particularly to a liquid crystal display device capable of realizing high transmittance with a simple electrode configuration in an in-plane switching (IPS) type liquid crystal display device. Related to the terminal device.

  Recently, due to advantages such as thinness, light weight, small size, and low power consumption, display devices using liquid crystals have been developed from large-sized terminal devices such as monitors and televisions (TVs), notebook personal computers, cash dispensers, and the like. It is widely installed and used in medium-sized terminal devices such as vending machines, and small terminal devices such as personal TVs, PDAs (Personal Digital Assistance: personal information terminals), mobile phones and portable game machines. The liquid crystal panel, which is the main component of this liquid crystal display device, displays information by controlling the alignment state of liquid crystal molecules with an electric field, but there are many modes depending on the combination of the type of liquid crystal molecules, the initial alignment state, and the direction of the electric field. Has been proposed. Among these modes, there are STN (Super Twisted Nematic) mode with a simple matrix structure and TN (Twisted Nematic) mode with an active matrix structure, which are most often used in conventional terminal devices. The liquid crystal panel has a narrow angle range in which gradation can be viewed correctly, and gradation reversal occurs when the liquid crystal panel deviates from the optimum observation position.

  This gradation reversal problem has not been a major problem in terminal devices whose display content is mainly text, for example, terminal devices such as mobile phones when only the phone number was displayed. However, due to recent technological progress, the terminal device has displayed not only character information but also a lot of image information, so that there is a problem that the visibility of the image is remarkably lowered due to the gradation inversion. For this reason, a liquid crystal panel having a wide viewing angle range in which gradation inversion does not occur and the gradation can be correctly recognized is gradually being mounted on the terminal device. The liquid crystal panel of such a mode is generally called a wide viewing angle liquid crystal panel, and a lateral electric field mode such as an IPS (in-plane switching) system, a multi-domain vertical alignment mode, and a film compensated TN mode are put into practical use. .

  Of the wide viewing angle modes employed in these wide viewing angle liquid crystal panels, the film compensation TN mode is obtained by bonding a viewing angle compensation film to a TN mode liquid crystal panel to improve the viewing angle. In the first place, in a TN mode liquid crystal panel, liquid crystal molecules are aligned so as to be parallel to the substrate when no voltage is applied. In the TN mode, since a liquid crystal having a uniaxial positive refractive index anisotropy is used, the direction in which the refractive index of liquid crystal molecules is large is aligned to be parallel to the substrate. When a voltage is applied in this state, the liquid crystal molecules rise in a direction perpendicular to the substrate, but due to the effect of the alignment regulating force of the alignment film that determines the initial alignment, the vicinity of the substrate interface does not rise completely even when a high voltage is applied. It is not possible to face the substrate diagonally. That is, the direction in which the refractive index of the liquid crystal molecules is large is present in an obliquely aligned state with respect to the substrate. Here, when the liquid crystal molecules are observed from a direction in which the refractive index is large, if the direction fluctuates even a little, the apparent refractive index of the liquid crystal molecules changes greatly, and the viewing angle becomes narrow due to this apparent refractive index change. turn into. Therefore, in the film compensation TN mode, the viewing angle compensation film functions to suppress a change in the apparent refractive index of the liquid crystal molecules aligned in the oblique direction. As an example of this, there is a compensation film in which a discotic compound is arranged so as to correspond to the liquid crystal molecules aligned in the oblique direction. When this compensation film is used, the influence of liquid crystal molecules in the vicinity of the substrate interface at the time of voltage application can be reduced, so that gradation inversion can be suppressed and viewing angle characteristics can be improved.

  Among the wide viewing angle modes described above, the multi-domain vertical alignment mode is a vertical alignment mode liquid crystal panel that has a vertical alignment state when no voltage is applied, and in which liquid crystal molecules are inclined in a direction parallel to the substrate interface when a voltage is applied. This is a system having domains in which the tilt directions compensate each other. When the liquid crystal molecules are tilted in only one direction when a voltage is applied, as in the vertical alignment mode that is not multi-domained, the field of view is affected by the liquid crystal molecules that are aligned in the oblique direction, as in the case of the TN mode voltage application described above. The corner becomes narrower. Therefore, in the multi-domain vertical alignment mode, a plurality of domains having different tilt directions are generated by providing irregularities on the substrate surface. That is, liquid crystal molecules tilted in a certain direction are optically compensated by liquid crystal molecules tilted in different directions of other domains, and the viewing angle is improved.

  These film-compensated TN mode and multi-domain vertical alignment mode improve the viewing angle by optically compensating for the influence of the tilted liquid crystal molecules, although the liquid crystal molecules tilt obliquely when a voltage is applied. It is common.

  On the other hand, the transverse electric field mode such as the IPS method has a wide viewing angle in principle because liquid crystal molecules do not tilt in an oblique direction with respect to the substrate even when a voltage is applied.

  FIG. 34 is a cross-sectional view schematically showing an IPS liquid crystal panel used in the first conventional liquid crystal display device described in Patent Document 1. In FIG. As shown in FIG. 34, in a conventional first liquid crystal panel 1300, liquid crystal molecules 1202 are sandwiched between a pair of substrates 1200 and 1201, and a pair of electrodes 1203 and 1204 are formed on the surface of the substrate 1201 on the liquid crystal molecule side. Has been placed. The pair of electrodes 1203 and 1204 are formed in the same layer and have a parallel electrode type electrode structure. Here, if the distance between the pair of substrates 1200 and 1201, that is, the cell gap is d, the width of the electrode is w, and the distance between the pair of electrodes is L, in the conventional IPS system, the relationship between these dimensions. Satisfies L / d> 1 and L / w> 1. That is, the distance between the electrodes is larger than the cell gap and larger than the electrode width. As shown in the figure, the direction in which the electrodes 1203 and 1204 are arranged is defined as the Y direction, and the direction in which the substrates 1200 and 1201 are stacked is defined as the Z direction. Further, the X direction is defined as a direction orthogonal to the Y direction and the Z direction, and each positive direction is a direction shown in the figure.

  In the conventional first liquid crystal panel described in Patent Document 1 configured as described above, by applying different voltages to the pair of electrodes 1203 and 1204, a lateral electric field E is generated between the pair of electrodes 1203 and 1204. Occurs. The lateral electric field E drives liquid crystal molecules positioned between the pair of electrodes 1203 and 1204. At this time, since the liquid crystal molecules rotate in the XY plane and do not rise in the Z direction, the user does not observe the liquid crystal molecules from the direction where the refractive index anisotropy is large. That is, the above-mentioned film compensation TN mode and multi-domain vertical alignment mode improve the viewing angle characteristics by reducing the influence of liquid crystal molecules rising in an oblique direction, whereas the IPS method is basically a liquid crystal molecule that Since it does not stand up in an oblique direction, it has very good viewing angle characteristics.

  FIG. 35 is a cross-sectional view schematically showing a liquid crystal panel used in the conventional second liquid crystal display device described in Patent Document 1. In FIG. This conventional second liquid crystal panel is a fringe-field switching (FFS) liquid crystal panel which is an improved version of the IPS system. As shown in FIG. 35, in a conventional second liquid crystal panel 2300, liquid crystal molecules 2202 are sandwiched between a pair of substrates 2200 and 2201, and an electrode 2204 is provided on the liquid crystal molecule side surface of the substrate 2201 from the substrate 2201 side. An insulating layer 2205 is laminated on the liquid crystal side of the electrode 2204, and the other electrode 2203 is formed thereon. The electrode 2203 is comb-like like the electrode described in the above-mentioned conventional first liquid crystal panel, whereas the electrode 2204 is not patterned into a comb-teeth. As in the above-described conventional first liquid crystal panel, if the distance between the substrates 2200 and 2201, that is, the cell gap is d, the width of the electrode 2203 is w, and the distance between the electrode 2203 and the electrode 2204 is L, In the FFS mode liquid crystal panel, L / d = 0 and L / w = 0 are established. That is, two types of electrodes are formed of different layers. Specifically, since the comb-shaped electrode 2203 is laminated on the electrode 2204 via the insulating layer 2205, the inter-electrode distance L becomes zero. ing.

  In the conventional second liquid crystal panel described in Patent Document 1 configured in this way, a horizontal electric field E is generated between the electrodes 2203 and 2204 by applying different voltages to the electrodes 2203 and 2204. The direction of the electric field differs depending on the difference in electrode configuration as compared with the case of the first liquid crystal panel. That is, in the first liquid crystal panel of the IPS method, the electrodes 1203 and 1204 have a parallel electrode structure in which the electrodes 1203 and 1204 are arranged in parallel to the Y direction as viewed from the Z direction. In the FFS system, since the electrodes 2203 and 2204 have a stacked electrode structure in which they are stacked in the Z direction, an electric field that is strong in the Z direction that is perpendicular to the substrate surface in the vicinity of the edge of the electrode 2203 in addition to the Y direction. Have ingredients.

  As a result, in the IPS mode, even though the liquid crystal molecules 1202 positioned between the electrodes 1203 and 1204 are driven, the liquid crystal molecules positioned above the electrodes are hardly driven. In the FFS mode, the liquid crystal molecules positioned between the electrodes 2203 are not driven. Of course, the liquid crystal molecules 2202 located above the electrode 2203 are also driven. Therefore, in the FFS method, if the electrode is formed of a transparent conductive film such as indium tin oxide (hereinafter abbreviated as ITO), the electrode portion can also contribute to display, and the same conditions There is an advantage that the transmittance can be increased as compared with the IPS liquid crystal panel.

  As another electrode structure of this FFS system, a stacked electrode type structure as shown in FIG. 35 is used instead of a laminated electrode type structure as shown in FIG. <1 and L / w <1, that is, it is described that the same effect can be obtained by making the interelectrode distance smaller than the cell gap and the electrode width.

JP 2002-296611 A

  However, the above-described conventional liquid crystal display device has the following problems. That is, in the conventional IPS system, since the liquid crystal molecules on the electrode cannot be driven as described above, the transmittance of the liquid crystal panel is lowered. In addition, in the conventional electrode stack type FFS system, unlike the conventional IPS system, liquid crystal molecules on the electrode can be driven, but the cost is increased because the electrode configuration is complicated and the number of manufacturing processes increases. These problems, that is, the increase in cost due to the decrease in transmittance and the increase in the number of manufacturing processes, become a serious problem particularly when mounted on a small-sized terminal device.

  The present invention has been made in view of such problems, and in particular, a liquid crystal display capable of realizing high transmittance with a simple electrode configuration in a liquid crystal display device of an in-plane switching (IPS) system. An object is to provide a device and a terminal device using the device.

A liquid crystal display device according to the present invention includes at least a substrate having parallel electrode pairs, and a liquid crystal layer disposed on the substrate, and a total value of widths and intervals of electrodes constituting the parallel electrode pairs is The liquid crystal layer is less than half the thickness of the liquid crystal layer, the liquid crystal molecules of the liquid crystal layer are driven by an electric field generated by the parallel electrode pair, and the electric field on the electrode has a vertical electric field component larger than a horizontal electric field component, and , an electric field between the electrodes is small vertical electric field component than the transverse electric field component, director direction of the liquid crystal molecules in the region away from the vicinity of the substrate between the electrodes and on the electrodes, respectively, between the electrodes and on the electrodes A region different from the electric field direction of the liquid crystal layer, and this region is at least half the thickness of the liquid crystal layer, and the electric field direction between the electrodes is closer to the counter substrate side than the central region in the thickness direction of the liquid crystal layer. Direction perpendicular to In the liquid crystal display device of horizontal electric field drive system with electric field region is present, the by increasing the horizontal electric field on the electrodes by the electrode width of the parallel electrode pair smaller than the thickness of the liquid crystal layer, the liquid crystal on the electrode The transverse electric field on the electrodes is configured such that the molecules change in orientation in the same manner as the liquid crystal molecules between the electrodes, and the twist elastic constant of the liquid crystal molecules is smaller than the bend elastic constant of the liquid crystal molecules. When the liquid crystal molecules in the vicinity of the substrate between the electrodes are twist-deformed by an electric field generated by the parallel electrode pair by reducing the attenuation of the twist deformation of the liquid crystal molecules due to, the electrodes follow the twist deformation and follow the twist deformation. similar twisted liquid crystal molecules and the liquid crystal molecules between the electrode from the vicinity of the substrate on between the electrodes to the liquid crystal molecules in the regions away in the thickness direction of the liquid crystal layer of the above The parallel electrode pair is formed to extend in parallel to a pixel separation direction that separates adjacent pixels in the lateral direction and is arranged in a direction perpendicular to the pixel separation direction. the electrode arrangement direction of said parallel electrode pair, an image of each pixel with the liquid crystal layer have a pixel enlarging means for enlarging optically, the distal end of the pixel electrode and the common electrode constituting the parallel electrode pair Is characterized in that an electrode portion perpendicular to the rubbing direction is formed as a reverse rotation domain prevention structure .

  In the present invention, the liquid crystal molecules on the electrodes can be changed in orientation in the same manner as the liquid crystal molecules between the electrodes when a voltage is applied, so that the transmittance on the electrodes can be improved and the liquid crystal display including the transmittance between the electrodes can be improved. The transmittance of the device can be increased. Furthermore, the transmittance in the vicinity of the electrodes can be increased not only on the electrodes but also between the electrodes. This effect is particularly large as compared with the conventional parallel electrode type IPS system in which the electrode width is equal to or larger than the thickness of the liquid crystal layer, so that a lateral electric field mode liquid crystal display device with high transmittance can be realized. Furthermore, in the liquid crystal display device of the present invention, since the alignment of the liquid crystal on the electrode is changed following the change in the alignment of the liquid crystal between the electrodes, the rise of the liquid crystal molecules can be suppressed. As a result, viewing angle characteristics can be improved.

  Moreover, it is preferable that the distance between the electrodes constituting the parallel electrode pair is not less than the width of the electrodes. Thereby, since the ratio of the electrode arrangement direction to the electric field generated by the parallel electrode pair can be improved, low voltage driving is possible.

In addition, since the twist elastic constant of the liquid crystal molecules is smaller than the bend elastic constant, the liquid crystal molecules on the electrodes change more easily following the liquid crystal molecules between the electrodes whose orientation has been changed by the electric field. In addition, the transmittance of the liquid crystal layer in the vicinity of the electrode can be improved more efficiently.

  The liquid crystal molecules of the liquid crystal layer may have positive dielectric anisotropy, and the liquid crystal when an electric field is generated in the parallel electrode pair in the liquid crystal layer on the electrodes constituting the parallel electrode pair. There are preferably liquid crystal molecules in which the director direction of the molecules is the arrangement direction of the electrodes constituting the parallel electrode pair. Thereby, the transmittance of the liquid crystal layer on the electrode can be improved more effectively.

  The liquid crystal molecules of the liquid crystal layer may have a negative dielectric anisotropy. Negative-type liquid crystal molecules with negative dielectric anisotropy change the orientation in the direction perpendicular to the electric field, so that follow-up to the vertical electric field can be prevented compared with the case of using positive-type liquid crystal molecules. Can be rotated more easily. Thereby, the transmittance on the electrodes can be significantly improved as compared with the positive type liquid crystal, and as a result, the transmittance of the liquid crystal display device including the transmittance between the electrodes can be increased. Furthermore, since the rise of liquid crystal molecules can be suppressed, the viewing angle characteristics can be improved.

  Furthermore, in the liquid crystal layer on the electrodes constituting the parallel electrode pair, the director direction of the liquid crystal molecules when an electric field is generated in the parallel electrode pair is the longitudinal direction of the electrodes constituting the parallel electrode pair. Preferably molecules are present. Thereby, in a liquid crystal display device using a liquid crystal having a negative dielectric anisotropy, the transmittance on the electrode can be improved.

  The parallel electrode pair may be formed in the same layer. This eliminates the need for a manufacturing process for laminating electrodes, thereby reducing the cost of the liquid crystal display device.

  Moreover, you may have an overcoat layer between the liquid-crystal layer side of the said parallel electrode pair, and the electrode which comprises this parallel electrode pair. As a result, the unevenness caused by the electrodes can be reduced, so that a high contrast ratio can be realized without impairing the orientation even if the electrode pitch is reduced.

  Moreover, you may have the planarization layer between the electrodes which comprise the said parallel electrode pair. As a result, the gap between the electrodes is filled with the flattening layer and flattened, so that not only can the orientation be improved as in the case of the above-described overcoat, but a flattening layer is provided on the electrodes. Therefore, the driving voltage can be reduced.

  The parallel electrode pair may be made of a transparent conductor. Thereby, it is possible to enjoy a part of the effect of the present invention, in particular, to increase the transmittance on the electrode.

  The parallel electrode pair may be made of metal. Thereby, the thinning of the electrode is facilitated and the transmittance in the vicinity of the electrode can be improved, so that the transmittance of the liquid crystal display device can be improved.

  Further, reflection reducing means can be provided on the surface of the parallel electrode pair on the liquid crystal layer side. Accordingly, it is possible to solve the problem that the display quality is deteriorated due to the reflection of the external light on the metal surface.

  Furthermore, it is preferable that the parallel electrode pair has an electrode width of 1 μm or less. Thereby, since the orientation of the liquid crystal molecules on the electrodes can be made the same as the orientation of the liquid crystal molecules between the electrodes, the transmittance can be further increased.

  The liquid crystal display device may operate in a normally white mode. In the present invention, since the liquid crystal layer acts as a retardation plate having a uniform orientation, light leakage during black display can be suppressed, and the display contrast ratio can be greatly improved.

Moreover, the electrode arrangement direction of said parallel electrode pair, that has a pixel enlarging means for enlarging the image of each pixel optically with the liquid crystal layer. In the present invention, since the liquid crystal layer has a uniform orientation and the in-plane transmittance fluctuation is suppressed, the pixel image enlarged by the pixel enlargement means can achieve uniform brightness and high image quality. It becomes. Thereby, a high-quality stereoscopic image display device, a multi-screen display device, and a bright liquid crystal display device with improved light utilization efficiency can be realized.

  In the present invention, more liquid crystal molecules can be twist-deformed than in the conventional method, and in particular, the liquid crystal molecules in a region away from the substrate can be more effectively twist-deformed. High transmittance can be realized.

  In the present invention, since the electric field near the center of the thickness of the liquid crystal layer where the anchoring force due to the alignment means of the liquid crystal layer is the weakest is weakened, the liquid crystal molecules can move more freely, and the liquid crystal layer Twist deformation can be efficiently performed, and higher transmittance can be realized. In addition, since the rising of the liquid crystal molecules in the direction perpendicular to the substrate surface can be suppressed, the viewing angle characteristics can be improved. Furthermore, since the liquid crystal layer can be uniformly twisted, a retardation plate with a uniform in-plane retardation distribution can be realized.

Further, the total value of the width and the interval of the electrodes constituting the parallel electrode pair is not more than half of the thickness of the liquid crystal layer, and on the counter substrate side from the central region in the thickness direction of the liquid crystal layer, between the electrodes field region exists an electric field direction is the direction perpendicular to the substrate surface. By generating the electric field structure according to the present invention using the parallel electrode pair structure, a vertical electric field can be generated not only on the electrodes but also between the electrodes in the vicinity of the counter substrate of the liquid crystal layer. As a result, the vertical electric field on the electrode that originally existed and the equipotential line are connected, and an equipotential line extending over a plurality of electrodes can be generated. Further, the weak electric field layer can be introduced near the center of the liquid crystal layer in the thickness direction, and twist deformation can be more easily performed on the counter substrate side half or more of the liquid crystal layer.

  Furthermore, it is preferable that the electrode width of the parallel electrode pair is 0.5 μm or less. Accordingly, in the present invention, the thickness of the liquid crystal layer can be set within a range of about 5 μm, and the anchoring energy of the alignment means can be effectively applied to the alignment deformation. Response time can be improved.

Furthermore, the that have reverse rotation domain preventing structure parallel electrode pair is formed. Thereby, undesirable orientation deformation of the liquid crystal molecules due to the end portions of the parallel electrode pair occurs, and the phenomenon of propagation to the entire parallel electrode pair can be suppressed, and stable twist deformation can be realized.

  The terminal device may be a mobile phone, a personal information terminal, a game machine, a digital camera, a video camera, a video player, a notebook personal computer, a cash dispenser, or a vending machine.

  According to the present invention, in an IPS liquid crystal display device having parallel electrode pairs, an electrode width of the parallel electrode pairs is formed to be smaller than a thickness of the liquid crystal layer, and an electric field generated by the parallel electrode pairs causes a gap between the electrodes. The orientation of the liquid crystal molecules changes and the orientation of the liquid crystal molecules on the electrodes changes following the orientation change in the same way as the liquid crystal molecules between the electrodes. The director direction of the liquid crystal molecules on the electrodes is different from the electric field on the electrodes. By doing so, the transmittance on the electrode and the transmittance in the vicinity of the electrode can be improved, whereby the transmittance of the liquid crystal display device can be improved with a simple electrode configuration.

  Hereinafter, a liquid crystal display device according to an embodiment of the present invention and a terminal device using the same will be described in detail with reference to the accompanying drawings. First, a liquid crystal display device according to a first embodiment of the present invention and a terminal device using the same will be described. FIG. 1 is a cross-sectional view showing a state when a voltage is applied to the liquid crystal display device according to the present embodiment, and FIG. 2 is an alignment state of liquid crystal molecules when no voltage is applied between the pixel electrode and the common electrode which are constituent elements thereof. FIG. 3 is a perspective view showing a terminal device equipped with the liquid crystal display device according to the present embodiment.

  As shown in FIG. 1, in the liquid crystal display device 1 according to the first embodiment, the main substrate 2a and the counter substrate 2b are arranged to face each other with a minute gap, and the main substrate 2a has a surface on the counter substrate 2b side. Are formed with two types of electrodes, a pixel electrode 3a and a common electrode 3b. These two types of electrodes are formed in a comb-teeth shape, and pixel electrodes 3a and common electrodes 3b are alternately arranged in a direction orthogonal to the longitudinal direction of the comb teeth (lateral direction in FIG. 1). These electrodes are made of a transparent conductor such as ITO (indium tin oxide). Further, an alignment film 4 for initial alignment of liquid crystal molecules is formed on the counter substrate 2b side. Similarly, the alignment film 4 is also formed on the surface of the counter substrate 2b on the main substrate 2a side. A layer made of positive-type liquid crystal molecules 51 having a positive dielectric anisotropy is sandwiched between the main substrate 2a and the counter substrate 2b. The gap between the main substrate 2a and the counter substrate 2b, that is, the thickness of the layer made of the positive liquid crystal molecules 51 is set to 3 μm as an example. In the present embodiment, the thickness of the layer made of liquid crystal molecules is referred to as a cell gap. In an actual liquid crystal display device, polarizing plates are provided on both sides of the liquid crystal display device 1, but are omitted in FIG. 1.

  In this specification, for convenience, an XYZ orthogonal coordinate system is set as follows. The direction from the main substrate 2a toward the counter substrate 2b is the + Z direction, and the opposite direction is the −Z direction. The + Z direction and the −Z direction are collectively referred to as the Z-axis direction. Further, the horizontal direction in FIG. 1 is the Y-axis direction, in particular, the right direction is the + Y direction, and the opposite direction is the -Y direction. The + X direction is a direction in which the right-handed coordinate system is established. That is, when the thumb of the person's right hand is oriented in the + X direction and the index finger is oriented in the + Y direction, the middle finger is oriented in the + Z direction.

  When the XYZ orthogonal coordinate system is set as described above, the direction in which the pixel electrodes 3a and the common electrodes 3b are alternately arranged is the Y-axis direction. Further, the direction in which the pixel electrode 3a or the common electrode 3b extends, that is, the comb tooth longitudinal direction of the comb-like electrode is the X-axis direction. The display surface of the liquid crystal display device 1 is an XY plane.

  As an example, the width of the pixel electrode 3a and the common electrode 3b, that is, the electrode width is formed to be 1 μm. In addition, the distance between the pixel electrode 3a and the common electrode 3b, that is, the inter-electrode distance is set to 6 μm as an example. As described above, since the cell gap in this embodiment is set to 3 μm, the electrode width is set to be smaller than the cell gap in this embodiment.

  As described above, in the IPS system used in the conventional first liquid crystal display device described in Patent Document 1, the electrode structure is a parallel electrode type, and L / d> 1 and L / w> 1, That is, the distance between the electrodes is defined to be larger than the cell gap and the distance between the electrodes is defined to be larger than the electrode width. However, in this embodiment, w / d <1, that is, the relationship that the electrode width is smaller than the cell gap is satisfied. Is.

  Further, in the FFS method used in the conventional second liquid crystal display device described in Patent Document 1, this embodiment has a parallel electrode type structure particularly for a method having a stacked electrode type structure. In order to have, the electrode structure is different. In the FFS method, particularly for a method having a parallel electrode type structure, as described above, the parallel electrode type FFS method is L / d <1 and L / w <1, that is, the inter-electrode distance is the cell gap and In this embodiment, the distance between the electrodes is larger than the cell gap and the electrode width, and in particular, the electrode width is smaller than the cell gap.

  When a group of liquid crystal molecules is deformed in response to an electric field, the splay elastic constant K11, the twist elastic constant K22, and the bend with respect to respective strains of spread (twist), twist (bend), and bend (bend). Elastic force acts according to the elastic constant K33.

  As an example, the positive liquid crystal molecule 51 has a refractive index anisotropy Δn of 0.1, a dielectric anisotropy Δε of 14 at a wavelength of 550 nm, a dielectric constant of 18.4 in a direction parallel to the alignment vector of the liquid crystal, and an elasticity. The constants have physical property values of K11 = 11.3 [pN] (piconewton), K22 = 6.9 [pN], K33 = 11.6 [pN]. This liquid crystal molecule has a twist elastic constant K22 smaller than the bend elastic constant K33, and is easily twisted.

  As shown in FIG. 2, the alignment state of the positive liquid crystal molecules 51 is such that the major axis direction of the liquid crystal molecules is substantially the X-axis direction in the initial state where no voltage is applied between the pixel electrode 3a and the common electrode 3b. Has been processed. Note that one of the two polarizing plates arranged on both sides of the liquid crystal display device 1 is arranged with its absorption axis aligned with the major axis direction of the liquid crystal molecules. Another polarizing plate is arranged so as to be orthogonally arranged.

  As shown in FIG. 1, the alignment state of the positive liquid crystal molecules 51 when a voltage that is a square wave of ± 5 V · 60 Hz is applied between the common electrode 3b and the pixel electrode 3a is as follows. In the vicinity of the interface of the counter substrate 2b, the alignment is almost in the X-axis direction due to the anchoring effect by the alignment treatment, but as the distance from the substrate interface, the alignment in the Y-axis direction follows the direction of the horizontal electric field generated by the parallel electrodes. It has changed. On the other hand, the liquid crystal alignment state on the electrodes remains in the initial alignment in the vicinity of the interface of the counter substrate 2b, as between the electrodes, but is aligned in the Y-axis direction in the same manner as between the electrodes as the distance from the counter substrate 2b increases. . In the vicinity of the pixel electrode 3a or the common electrode 3b on the main substrate 2a, although a slight rise in the Z-axis direction is observed, the thickness of the liquid crystal layer in that portion is smaller than 1 μm.

  That is, in the IPS system used in the conventional first liquid crystal display device described in Patent Document 1, as described above, the liquid crystal molecules located above the electrodes are hardly driven, whereas this embodiment is implemented. The liquid crystal molecules on the electrodes in the form are different in that the orientation changes in the Y-axis direction, similar to the orientation direction of the liquid crystal molecules between the electrodes.

  Further, in the FFS system used in the conventional second liquid crystal display device described in Patent Document 1, both the parallel electrode type and the stacked electrode type have a strong Z direction generated due to a small inter-electrode distance. Although the liquid crystal molecules on the electrodes are changed in orientation by the electric field component, the liquid crystal molecules on the electrodes in this embodiment are mostly aligned in the Y-axis direction following the change in the orientation of the liquid crystal molecules between the electrodes. It has changed.

  As shown in FIG. 3, the liquid crystal display device 1 is mounted on, for example, a mobile phone 9.

  Next, the operation of the liquid crystal display device according to this embodiment configured as described above, that is, the light modulation operation of the liquid crystal display device according to this embodiment will be described. FIG. 4 is a photomicrograph for showing the transmittance distribution of the liquid crystal display device when no voltage is applied between the common electrode and the pixel electrode, and FIG. 5 is ± 5 V between the common electrode and the pixel electrode. FIG. 6 is a micrograph for showing a transmittance distribution of a liquid crystal display device when a rectangular wave voltage of 60 Hz is applied, and FIG. 6 is a graph in which voltage-transmittance characteristics are measured in a region having a diameter of 1 μm at the center between electrodes. 7 is a graph obtained by measuring the voltage-transmittance characteristics in a 1 μm diameter region on the electrode. FIG. 8 is a graph showing the liquid crystal alignment and the liquid crystal alignment in order to analyze the operation principle of the liquid crystal display device when a voltage is applied. FIG. 9 is a result of simulating electric field distribution and transmittance distribution. FIG. 9 is an enlarged view showing liquid crystal alignment on the electrode in the simulation result of FIG. 8, and FIG. 10 is a 100 μm diameter including the electrode and between the electrodes. It is a graph of transmittance characteristics - voltage at the frequency.

  As shown in FIG. 4, when no voltage is applied between the common electrode and the pixel electrode, the major axis direction of the liquid crystal molecules coincides with the absorption axis direction of the polarizing plate, and the two polarizing plates are orthogonal to the absorption axis. Therefore, the transmittance becomes very small, that is, a so-called black state.

  Next, as shown in FIG. 5, when a voltage is applied between the common electrode and the pixel electrode, a white state in which the transmittance increases is obtained, but in this embodiment, not only the region between the electrodes, In particular, the region on the electrode is also characterized by an increase in transmittance. In order to examine this transmittance value, the result of measuring the voltage-transmittance characteristics in the region of 1 μm diameter in the central part between the electrodes is the graph of FIG. 6. Similarly, in the region of 1 μm diameter on the electrode, the voltage -The result of having measured the transmittance | permeability characteristic is the graph of FIG. The value of transmittance is defined as 100% when the absorption axes of two polarizing plates are arranged in parallel in order to eliminate the influence of the optical characteristics of the polarizing plate. Respective voltages are applied from 0V to 5V. In the central portion between the electrodes, a maximum transmittance of 64% is obtained at a voltage of 4.5V. Similarly, on the electrode, a maximum transmittance of 47% is obtained at a voltage of 4.5V. The transmittance value on the electrode is larger than that of the conventional IPS system having a large electrode width.

  In order for the transmittance on the electrode to increase by applying a voltage, the alignment direction of the liquid crystal molecules on the electrode needs to be changed so that the transmittance increases by applying the voltage. Specifically, as in the case of liquid crystal molecules between electrodes, it is only necessary that the orientation change so that the orientation vector of the liquid crystal molecules is in the Y-axis direction. Therefore, in order to analyze the change in orientation of the liquid crystal molecules on this electrode, the behavior and electric field distribution of the liquid crystal molecules were verified using a commercially available liquid crystal orientation simulator. The results are shown in FIG. 8, which is particularly shown for the YZ plane. The electric field distribution indicates equipotential lines having the same potential. As shown in FIG. 8, since the direction of the electric field is in the Y-axis direction, particularly near the center between the electrodes, the liquid crystal molecules are greatly rotated in the Y-axis direction. In the vicinity of the substrate in the inter-electrode region, liquid crystal molecules are generated in which the liquid crystal molecules do not rotate in the Y-axis direction due to the anchoring effect due to the alignment treatment, but the ratio with respect to the Z-axis direction is very small. On the other hand, focusing on the region on the electrode, since the electric field is almost in the + Z direction, the liquid crystal molecules in the immediate vicinity of the electrode show a slight rise due to the generated vertical electric field in the Z-axis direction (see FIG. 9). ), The ratio of the angle and the Z-axis direction is small. It can be seen that most liquid crystal molecules are largely rotated in the Y-axis direction, like the liquid crystal molecules between the electrodes, without following the direction of the electric field. That is, in a region other than the vicinity of the electrode on the electrode, the liquid crystal molecules do not change in the vertical electric field direction in the Z-axis direction, and rotate in the Y-axis direction following the liquid crystal molecule alignment between the electrodes. As a result, the transmittance on the electrode increases.

  The reason why the liquid crystal molecules on the electrodes follow the liquid crystal alignment between the electrodes against the longitudinal electric field is that the electrode width is smaller than the cell gap. This allows the liquid crystal molecules on the electrodes to follow the liquid crystal alignment between the electrodes rather than being constrained by the initial alignment at the substrate interface, because the area in contact with the liquid crystal molecules between the electrodes is larger than the region in contact with the substrate interface. It becomes easy. As described above, in the conventional IPS method described in Patent Document 1, the liquid crystal molecules on the electrode hardly change their orientation from the initial orientation even when a voltage is applied, but this is because the substrate interface is more constrained. it is conceivable that. In the present embodiment, since the electrode width is formed smaller than the cell gap, the binding at the substrate interface is relatively lowered, and the liquid crystal alignment between the electrodes is easily followed.

  That is, the liquid crystal molecules on the electrodes are more energetically stable when they are twist-deformed following the liquid crystal alignment between the electrodes against the electric field, rather than staying in the initial alignment against the electric field. .

  Furthermore, since the liquid crystal molecules on the electrodes follow the liquid crystal alignment between the electrodes, the liquid crystal molecules in the vicinity of the electrodes are more likely to be twist-deformed as compared with the conventional IPS. It is done.

  In addition, since the free energy at the time of twist deformation can be reduced by making the twist elastic constant K22 of the liquid crystal molecule smaller than the bend elastic constant K33 like the positive liquid crystal molecule 51 in the present embodiment, the liquid crystal molecule on the electrode can be reduced. Becomes more easily twist-deformed following the liquid crystal molecules between the electrodes. Thereby, the transmittance of the liquid crystal layer on the electrode can be improved more efficiently.

  As shown in FIG. 10, the maximum transmittance in this embodiment is 56%, which is about 1.3 times that of the conventional IPS system shown in the first comparative example of the present invention described later. The transmittance is improved.

  According to the liquid crystal display device of the present invention, in a horizontal electric field mode liquid crystal display device having comb-like parallel electrodes, the orientation of liquid crystal molecules on the electrodes can be changed in the same manner as the liquid crystal molecules between the electrodes when a voltage is applied. Therefore, in particular, the transmittance on the electrodes can be improved, and the transmittance of the liquid crystal display device including the transmittance between the electrodes can be increased. Furthermore, the transmittance in the vicinity of the electrodes can be increased not only on the electrodes but also between the electrodes. This effect is particularly large as compared with the conventional parallel electrode type IPS system in which the electrode width is equal to or larger than the cell gap, so that a lateral electric field mode liquid crystal display device with high transmittance can be realized.

  In particular, when compared with the conventional laminated electrode type FFS method, the liquid crystal display device of the present invention can increase the transmittance with a parallel electrode type structure in which electrodes are not laminated. Thereby, since it can implement | achieve without using a complicated lamination process, the cost reduction of a liquid crystal display device is attained.

  In particular, when compared with the conventional parallel electrode type FFS method, the liquid crystal display device of the present invention can provide a large space between the pixel electrode and the common electrode, thereby reducing the probability of occurrence of a short circuit between the two electrodes. Can be manufactured at a high yield.

  Further, in both the stacked electrode type and the parallel electrode type FFS methods, the liquid crystal molecules on the electrodes are changed in orientation by a strong electric field component in the Z direction generated by a small interelectrode distance, whereas the liquid crystal of the present invention is changed. Since the display device changes the alignment of the liquid crystal on the electrodes by following the change in the alignment of the liquid crystal between the electrodes, the rising of the liquid crystal molecules in the Z-axis direction can be suppressed. As a result, since the rising of the liquid crystal molecules in the oblique direction can be suppressed as compared with the FFS method, the viewing angle characteristics can be improved.

  Furthermore, in the liquid crystal display device of the present invention, since the alignment direction of the liquid crystal molecules between the electrodes and the liquid crystal molecules on the electrodes can be aligned, the refractive index distribution in the Y-axis direction can be reduced, thereby suppressing the occurrence of diffraction. it can. Light traveling in an oblique direction due to diffraction lowers the contrast. Therefore, by suppressing this diffraction phenomenon, viewing angle characteristics such as high contrast can be improved.

  The portable terminal device provided with the liquid crystal display device of the present invention can display with high luminance because the transmittance of the liquid crystal display device is high. In addition, when used at a luminance of a conventional level, the amount of light from the backlight can be suppressed, so that power can be reduced. Further, if the conventional power can be used with the brightness of the conventional level, the improvement in the transmittance can be directed to the increase in the number of pixels, so that more information can be displayed. This is particularly suitable for portable terminal devices with limited screen sizes.

  In addition, although the liquid crystal display device of this embodiment described the example in which the pixel electrode and the common electrode are configured by a transparent conductor such as ITO, the present invention is not limited thereto, and is configured by an optically opaque metal. May be. In general, a metal such as aluminum has a higher workability than ITO, so that the electrodes can be easily miniaturized. On the other hand, the ratio of the orientation on the electrode that contributes to the improvement of transmittance is slightly reduced by making the electrode opaque, but as described above, the effect of improving the transmittance by miniaturization can be obtained even in the vicinity of the electrode. Therefore, the transmittance can be improved when combined. In addition, when forming an electrode with a metal in this way, it is better to make the electrode width as small as possible, and it is particularly preferable to make it less than 1 μm.

  Moreover, in the liquid crystal display device of this embodiment, although it described as having an alignment film in the board | substrate side interface of a liquid crystal molecule, this invention is not limited to this, It seems that a liquid crystal molecule aligns in a predetermined direction. Therefore, it is not an essential component of the present invention.

  In the liquid crystal display device of this embodiment, the case where the pixel electrode and the common electrode are formed in the same layer has been described. However, the present invention is not limited to this, and the parallel electrode type may be provided in different layers. It may be formed, and an insulating layer may be formed between the different electrode layers. In particular, when applied to an active matrix type, a pixel electrode and a common electrode can be formed using a gate electrode forming a thin film transistor of a pixel and a source or drain electrode, and a new layer is provided for a parallel electrode. Since it is not necessary, the cost can be reduced.

  Further, the pixel electrode and the common electrode have been described as having the longitudinal direction in the X-axis direction. However, the present invention is not limited to this, and the pixel electrode and the common electrode may be arranged inclined with respect to the X-axis direction. Alternatively, this slope may be multi-domained with different values depending on the coordinates on the X axis.

  As described above, the liquid crystal display device of the present invention can be suitably applied to a mobile terminal device such as a mobile phone. The mobile terminal device can be applied not only to a mobile phone but also to various mobile terminal devices such as a PDA (Personal Digital Assistant), a game machine, a digital camera, and a digital video camera. Further, the present invention can be applied not only to portable terminal devices but also to various terminal devices such as notebook personal computers, cash dispensers, and vending machines.

  Next, a first comparative example for the liquid crystal display device of the present invention will be described. FIG. 11 is a cross-sectional view showing a state when a voltage is applied to the liquid crystal display device according to this comparative example, and FIG. 12 shows a case where a ± 5 V / 60 Hz rectangular wave voltage is applied between the common electrode and the pixel electrode. FIG. 13 is a photomicrograph for showing the transmittance distribution of the liquid crystal display device of this comparative example, FIG. 13 is a graph in which the voltage-transmittance characteristics are measured in a region having a diameter of 1 μm at the center between the electrodes, and FIG. FIG. 15 is a graph showing the voltage-transmittance characteristics measured in a 1 μm diameter region on the electrode. FIG. 15 shows the liquid crystal alignment, electric field distribution, and transmittance distribution in order to analyze the operating principle of the liquid crystal display device when a voltage is applied. FIG. 16 is an enlarged view showing the liquid crystal alignment on the electrodes in the simulation result of FIG. 15, and FIG. 17 shows the voltage in a region of 100 μm in diameter including the electrodes and between the electrodes. It is a graph of transmittance characteristic.

  As shown in FIG. 11, the liquid crystal display device 11 shown in the first comparative example is different from the liquid crystal display device 1 in the first embodiment in that the electrode width is set larger. In other words, in the first embodiment, the electrode width of the pixel electrode 3a and the common electrode 3b is 1 μm, whereas in the first comparative example, the electrode width of the pixel electrode 31a and the common electrode 31b is 3 μm. ing. Since the value of the cell gap is set to 3 μm as in the first embodiment, the electrode width and the cell gap are the same in this comparative example.

  Furthermore, the alignment state of the positive liquid crystal molecules 51 when a voltage is applied is aligned in the X-axis direction in the vicinity of the interface of the main substrate 2a or the counter substrate 2b between the electrodes due to the anchoring effect by the alignment process. As the distance from the substrate interface increases, the orientation changes in the Y-axis direction according to the direction of the transverse electric field generated by the parallel electrodes. This is the same as the first embodiment. On the other hand, the liquid crystal alignment state on the electrodes remains in the initial alignment in the vicinity of the interface of the counter substrate 2b, as between the electrodes, and does not align in the Y-axis direction even when separated from the counter substrate 2b. I keep it. That is, in the first embodiment, the liquid crystal molecules on the electrode are changed in the Y-axis direction in the portion away from the counter substrate 2b, whereas in this comparative example, the liquid crystal molecules are not changed in the Y-axis direction. Different. Other configurations in the comparative example are the same as those in the first embodiment described above.

  The first comparative example is the same as the IPS method used in the conventional first liquid crystal display device described in Patent Document 1. That is, the electrode width has a value equal to or larger than the cell gap, and the liquid crystal molecules located above the electrode are hardly driven.

  Next, the operation of the liquid crystal display device according to the first comparative example configured as described above will be described. As shown in FIG. 12, when a voltage is applied between the common electrode and the pixel electrode, a white state in which the transmittance is increased is obtained, but in this comparative example, the transmittance is increased in the region between the electrodes. Although it is observed brightly in the photograph, it is considered that the area on the electrode is dark and the transmittance is greatly reduced. Therefore, in order to examine the value of the transmittance, the result of measuring the voltage-transmittance characteristics in the region having a diameter of 1 μm at the center portion between the electrodes is the graph of FIG. 13. Similarly, in the region having a diameter of 1 μm on the electrode. FIG. 14 is a graph showing the results of measuring the voltage-transmittance characteristics. Each voltage is applied from 0V to 5V. In the central portion between the electrodes, a maximum transmittance of 59% is obtained at a voltage of 4.1V. On the other hand, on the electrode, similarly, the transmittance becomes maximum at a voltage of 4.1 V, and the value remains at 24%. In other words, the transmittance value between the electrodes is greatly reduced although the result of the transmittance between the electrodes is almost the same as that of the first embodiment.

  Next, in order to examine the decrease in transmittance on the electrode, the orientation, electric field distribution, and transmittance distribution of liquid crystal molecules were analyzed using a commercially available liquid crystal alignment simulator. The result is shown in FIG. FIG. 16 is an enlarged view of the liquid crystal alignment on the electrode in the result of FIG. As shown in FIG. 15, since the direction of the electric field is in the Y-axis direction, particularly near the center between the electrodes, the liquid crystal molecules are greatly rotated in the Y-axis direction. As a result, the transmittance is improved. . On the other hand, the transmittance is reduced in the region on the electrode. As shown in FIG. 16, the liquid crystal molecules on the electrode hardly follow the change in alignment between the electrodes and maintain the initial alignment. Is the reason. That is, in the conventional IPS system, liquid crystal molecules positioned above the electrode are hardly driven, and as a result, the transmittance on the electrode does not increase.

  Furthermore, as shown in FIG. 17, the maximum transmittance including on and between the electrodes is 44%, which is reduced by a factor of 1.3 as compared with the first embodiment. As described above, in the conventional IPS system, it was confirmed that the transmittance of the liquid crystal display device was lowered because the liquid crystal molecules on the electrode did not contribute to the improvement of the transmittance.

  Next, a second comparative example for the liquid crystal display device of the present invention will be described. FIG. 18 is a graph obtained by measuring the voltage-transmittance characteristics of the liquid crystal display device of this comparative example in a region having a diameter of 100 μm including between and between the electrodes.

  The second comparative example is different from the first comparative example in that the electrode width is set larger. That is, the electrode width in the first comparative example was 3 μm, whereas in the second comparative example, it was 6 μm. Other configurations in the present comparative example are the same as those in the first comparative example.

  In this comparative example, as shown in FIG. 18, the maximum transmittance is reduced to 39%. That is, it is understood that the transmittance decreases as the electrode width with respect to the cell gap is increased.

  Next, a liquid crystal display device according to a second embodiment of the present invention will be described. FIG. 19 is a cross-sectional view showing a state when a voltage is applied to the liquid crystal display device according to this embodiment, and FIG. 20 is an alignment state of liquid crystal molecules when no voltage is applied between the pixel electrode and the common electrode which are constituent elements thereof. FIG. 21 is a graph showing voltage-transmittance characteristics measured in a region having a diameter of 100 μm including on and between electrodes.

  As shown in FIG. 19, in the liquid crystal display device 12 shown in the second embodiment, the pixel electrode 3a and the common electrode 3b having a width of 1 μm are used instead of the liquid crystal display device 1 in the first embodiment. A pixel electrode 32a and a common electrode 32b having a width of 1.5 μm are used. The distance between the pixel electrode 32a and the common electrode 32b, that is, the interelectrode distance is set to 3.8 μm. Further, a layer made of negative liquid crystal molecules 52 having a negative dielectric anisotropy is sandwiched between the main substrate 2a and the counter substrate 2b. The gap between the main substrate 2a and the counter substrate 2b, that is, the thickness of the layer made of the negative liquid crystal molecules 52 is set to 3.5 μm. That is, in the second embodiment, the values of the electrode width, the inter-electrode distance, and the cell gap are different from the first embodiment, but are the same in that the electrode width is formed smaller than the cell gap.

  For example, the negative liquid crystal molecule 52 has a refractive index anisotropy Δn of 0.1 at a wavelength of 550 nm, a dielectric anisotropy Δε of −6.2, and a dielectric constant in a direction parallel to the alignment vector of the liquid crystal of 4. 1. The elastic constants have physical property values of K11 = 14.6 [pN], K22 = 6.7 [pN], K33 = 15.7 [pN]. The negative liquid crystal is a liquid crystal in which the dielectric constant in the direction parallel to the alignment vector of the liquid crystal is smaller than the dielectric constant in the direction perpendicular to the alignment vector, and the dielectric anisotropy has a negative value. Since the direction with a large dielectric constant is orthogonal to the direction of the orientation vector, the orientation changes perpendicular to the electric field. Since the liquid crystal molecule has a twist elastic constant K22 smaller than the bend elastic constant K33, as described in the first embodiment, the twist deformation is easy, and the transmittance of the liquid crystal layer on the electrode is further increased. It can be improved efficiently.

  As shown in FIG. 20, in the state in which no voltage is applied between the pixel electrode 32a and the common electrode 32b, that is, the alignment state of the negative liquid crystal molecules 52 as an initial state, the major axis direction of the liquid crystal molecules is substantially the Y-axis direction. Orientation treatment is performed.

  As shown in FIG. 19, the alignment state of the negative liquid crystal molecules 52 when a voltage that is a square wave of ± 6 V · 60 Hz is applied between the common electrode 32b and the pixel electrode 32a is as follows. In the vicinity of the interface of the counter substrate 2b, the alignment is almost in the Y-axis direction due to the anchoring effect due to the alignment treatment, but as the distance from the substrate interface increases, the X direction is perpendicular to the direction of the transverse electric field generated by the parallel electrodes. The orientation changes in the axial direction. On the other hand, the liquid crystal alignment state on the electrodes remains in the initial alignment in the vicinity of the interface of the counter substrate 2b, as between the electrodes, but is aligned in the X-axis direction in the same manner as between the electrodes as the distance from the counter substrate 2b increases. . In the vicinity of the pixel electrode 32a or the common electrode 32b on the main substrate 2a, although a slight rise in the Z-axis direction is observed, the thickness of the liquid crystal layer at that portion is smaller than 1 μm and smaller than in the case of the first embodiment. . Other configurations in the present embodiment are the same as those in the first embodiment.

  Next, the operation of the liquid crystal display device according to the second embodiment configured as described above will be described. As shown in FIG. 19, when a voltage is applied between the common electrode and the pixel electrode, a white state in which the transmittance increases is obtained, but in the present embodiment, the region between the electrodes has a large transmittance. In the region on the electrode, higher transmittance than that of the first embodiment can be realized. As a result, as shown in FIG. 21, the maximum transmittance including on and between the electrodes is 77%, and the transmittance is 1.37 times that of the first embodiment. . Further, a high transmittance of 1.75 times is obtained as compared with the conventional IPS system described in the first comparative example.

  Therefore, in order to examine the transmittance and liquid crystal alignment on the electrode when using negative type liquid crystal, a commercially available liquid crystal alignment simulator was used to analyze the alignment, electric field distribution, and transmittance distribution of liquid crystal molecules. The result is shown in FIG. FIG. 23 is an enlarged view of the liquid crystal alignment on the electrode in the result of FIG. As shown in FIGS. 22 and 23, since the direction of the electric field is the Y-axis direction, particularly near the center between the electrodes, the liquid crystal molecules are greatly rotated in the X-axis direction, which is a direction perpendicular to the electric field. As a result, the transmittance is improved. In the vicinity of the substrate in the inter-electrode region, liquid crystal molecules are generated in which the liquid crystal molecules do not rotate in the X-axis direction due to the anchoring effect due to the alignment treatment, but the ratio to the Z-axis direction is very small. On the other hand, focusing on the area on the electrodes, the liquid crystal molecules near the center between the substrates follow the change in the orientation of the liquid crystal molecules between the electrodes and rotate greatly in the X-axis direction. As a result, the transmittance is improved. is doing. In the vicinity of the electrode, a vertical electric field is generated in the Z-axis direction. However, in the case of negative liquid crystal, the orientation changes so that the orientation vector and the electric field are orthogonal to each other, and therefore the electric field does not hinder the rotation in the X-axis direction. For this reason, unlike the case of the positive liquid crystal molecules of the first embodiment, the liquid crystal molecules on the electrode can rotate more freely in the X-axis direction, so that the transmittance on the electrode can be further improved. . In addition, since the liquid crystal molecules do not rotate in the Z direction following the longitudinal electric field, the rise of the liquid crystal molecules in the vicinity of the electrode can be prevented, which is another factor that can improve the transmittance on the electrode.

  According to the liquid crystal display device of this embodiment, the electrode width is smaller than the cell gap, and negative type liquid crystal molecules are used, and the liquid crystal molecules on the electrodes are the same as the liquid crystal molecules between the electrodes when a voltage is applied. Since the orientation can be changed, the transmittance on the electrodes can be improved, and the transmittance of the liquid crystal display device including the transmittance between the electrodes can be increased. In particular, since negative-type liquid crystal molecules change orientation in a direction perpendicular to the electric field, follow-up to a vertical electric field can be prevented and rotation in the XY plane can be made easier than when positive-type liquid crystal molecules are used. . As a result, the transmittance on the electrodes can be significantly improved as compared with the positive type liquid crystal, and as a result, the transmittance of the liquid crystal display device including the transmittance between the electrodes can be increased. Furthermore, since the rising of the liquid crystal molecules in the Z-axis direction can be suppressed, the viewing angle characteristics can be improved. Operations and effects other than those described above in the second embodiment are the same as those in the first embodiment.

  Next, a liquid crystal display device according to a third embodiment of the present invention will be described. FIG. 24 is a graph obtained by measuring voltage-transmittance characteristics in a region having a diameter of 100 μm including and between the electrodes of the liquid crystal display device according to the present embodiment.

  The liquid crystal display device according to the third embodiment has a width of 1 μm instead of the pixel electrode 32a and the common electrode 32b having a width of 1.5 μm, as compared with the liquid crystal display device 12 according to the second embodiment. A pixel electrode and a common electrode are used. In addition, the distance between the pixel electrode and the common electrode, that is, the distance between the electrodes is set to 3.8 μm in the second embodiment, but is set to 1 μm in the present embodiment. The cell gap is 3.5 μm as in the second embodiment. That is, in this embodiment, the electrode width and the inter-electrode distance are set to the same value, and the electrode width is smaller than the gap, and in particular, the electrode pitch that is the sum of the electrode width and the inter-electrode distance is set to be equal to or less than the cell gap. Is different. Thus, in this embodiment, L / w ≧ 1, w / d <1, and (L + w) / d ≦ 1, that is, the interelectrode distance is equal to or greater than the electrode width, the electrode width is smaller than the cell gap, and the electrode This satisfies the condition that the pitch is smaller than the cell gap. In the present embodiment, since the electrode pitch is equal to or less than the cell gap, the electric field in the Y-axis direction is stronger than in the second embodiment. As a result, the liquid crystal alignment during voltage application in the present embodiment is such that more liquid crystal molecules on the electrode change in the X-axis direction. Other configurations in the present embodiment are the same as those in the second embodiment described above.

  Next, the operation of the liquid crystal display device according to the third embodiment configured as described above will be described. Similar to the liquid crystal display device of the second embodiment, when a voltage is applied between the common electrode and the pixel electrode, a white state is obtained in which the transmittance increases. As described above, the liquid crystal alignment on the electrode at this time is one in which more liquid crystal molecules are changed in alignment in the X-axis direction than in the second embodiment, so that higher transmittance can be realized. As shown in FIG. 24, the maximum transmittance including on and between the electrodes is 79%, and the transmittance is 1.41 times that of the first embodiment. Further, the transmittance as high as 1.8 times is obtained as compared with the conventional IPS system described in the first comparative example. Further, in the second embodiment, the voltage for realizing the maximum transmittance is 5.5V, whereas in the present embodiment, the voltage can be reduced to 5.0V and the power can be reduced.

  Note that the liquid crystal display device of this embodiment may have an overcoat layer for the purpose of planarization on the liquid crystal layer side of the pixel electrode and the common electrode. As described above, when using negative liquid crystal molecules, it is necessary to perform initial alignment so that the director direction of the liquid crystal molecules is substantially parallel to the alignment direction of the common electrode and the pixel electrode. When smaller than the cell gap, the liquid crystal molecules are aligned along the irregularities of the electrode. By providing the overcoat, the unevenness caused by the electrodes can be reduced, so that even if the electrode pitch is reduced, the orientation is not impaired and a high contrast ratio can be realized.

  Further, the planarization layer is provided only between the common electrode and the pixel electrode, and the planarization layer may not be provided on the common electrode and the pixel electrode. Thereby, since the gap between the common electrode and the pixel electrode is filled with the flattening layer and flattened, the orientation can be improved as in the case where the overcoat is provided. Furthermore, since the planarization layer is not provided on the electrode, the driving voltage can be reduced. Operations and effects other than those described above in the third embodiment are the same as those in the second embodiment.

  Next, a liquid crystal display device according to a fourth embodiment of the present invention is described. FIG. 25 is a cross-sectional view showing the structure of the liquid crystal display device according to the present embodiment and the alignment state of liquid crystal molecules when no voltage is applied between the pixel electrode and the common electrode, which are constituent elements thereof. It is sectional drawing which shows the electric field structure and liquid crystal orientation at the time of the voltage application of the liquid crystal display device of 4th Embodiment, It is sectional drawing which showed especially the relationship between an electric field structure, liquid crystal orientation, and transmittance | permeability distribution by simulation.

  As shown in FIG. 25, the liquid crystal display device 13 shown in the fourth embodiment has a pixel electrode 3a and a common electrode 3b each having a width of 1 μm as compared with the liquid crystal display device 1 in the first embodiment of the present invention described above. Instead, a pixel electrode 33a and a common electrode 33b having a width of 0.5 μm are used. The distance between the pixel electrode 33a and the common electrode 33b, that is, the interelectrode distance is set to 2.5 μm. Furthermore, a layer made of the same positive liquid crystal molecules 51 as in the first embodiment is sandwiched between the main substrate 2a and the counter substrate 2b. The gap between the main substrate 2a and the counter substrate 2b, that is, the thickness of the layer made of the positive liquid crystal molecules 51 is set to 4 μm. In the state in which no voltage is applied between the pixel electrode 33a and the common electrode 33b, that is, the alignment state of the positive liquid crystal molecules 51 as an initial state, the major axis direction of the liquid crystal molecules is substantially X as in the alignment state of the first embodiment. Orientation treatment is performed so as to be in the axial direction. As described above, the first feature of the structure in the fourth embodiment is that the sum of the electrode width and the inter-electrode distance is equal to or less than the thickness of the liquid crystal layer.

  FIG. 26 shows the electric field structure and liquid crystal alignment when a voltage is applied to the liquid crystal display device according to the fourth embodiment. In particular, the relationship between the electric field structure and the alignment of liquid crystal molecules and the transmittance distribution is measured using a commercially available liquid crystal alignment simulator. It is sectional drawing shown. A voltage that is a square wave of ± 5 V · 60 Hz is applied between the common electrode 33b and the pixel electrode 33a.

  As shown in FIG. 26, the second feature of the structure of the fourth embodiment relates to the electric field structure, and has an electric field region in which the electric field strength between the electrodes in the vicinity of the counter substrate is equal to or lower than the electric field strength on the electrodes. And Further, the third feature of the structure in the fourth embodiment relates to a liquid crystal alignment structure, and due to this electric field structure, the liquid crystal molecules on the electrodes change their orientation in the same manner as the liquid crystal molecules between the electrodes. In the meantime, the director direction of the liquid crystal molecules has a region different from the electric field direction. Other configurations in the present embodiment are the same as those in the first embodiment.

  Next, the operation of the liquid crystal display device according to the fourth embodiment configured as described above will be described. First, the electric field structure which is the second feature of the structure according to the present embodiment will be described. As described above, the electric field structure of the present invention is characterized by having a region where the electric field strength between the electrodes in the vicinity of the counter substrate is equal to or lower than the electric field strength on the electrodes. Here, paying attention to the simulation result of the transmittance shown in FIG. 26, the transmittance including on and between the electrodes is 83%, even when compared with the first to third embodiments of the present invention. Very high transmittance has been achieved. As a result of intensive studies on the results, the inventors have invented an electric field structure that can achieve very high transmittance even when positive liquid crystal molecules are used. As described above, the electric field structure of the present invention is characterized by having a region where the electric field strength between the electrodes in the vicinity of the counter substrate is equal to or lower than the electric field strength on the electrodes. In the case of having a tooth electrode, by introducing this electric field structure, a weak electric field layer having a very weak electric field can be generated in the liquid crystal layer near the counter substrate. The introduction of the weak electric field layer is one of the important concepts in the present embodiment, which is a feature that is greatly different from the conventional IPS system and the first embodiment. In the present embodiment, it is possible to achieve a high transmittance by inventing the electric field structure in which the weak electric field layer is introduced.

  Here, in order to describe the weak electric field layer, FIG. 26 which is a simulation result in the fourth embodiment, FIG. 15 which is a simulation result of the electric field structure described in the first comparative example, and the first embodiment described above. FIG. 8 which is a simulation result of the electric field structure described in the embodiment is compared. In the conventional electric field structure shown in FIG. 15, equipotential lines run between the electrodes in a direction perpendicular to the substrate surface, that is, in the Z-axis direction. The equipotential lines on the electrodes run in a direction substantially parallel to the substrate surface, that is, in the Y-axis direction in the cross-sectional view of FIG. In the conventional electric field structure, a transverse electric field is generated between the electrodes to realize twist deformation of the liquid crystal alignment, but a relatively strong electric field is generated on the electrodes in a direction perpendicular to the substrate surface, and the twist deformation of the liquid crystal alignment is achieved. Was hindering. As a result, the transmittance on the electrode was lowered. On the other hand, in the first embodiment of the present invention shown in FIG. 8, since the liquid crystal alignment on the electrodes follows the liquid crystal alignment between the electrodes, the transmittance on the electrodes is improved as compared with the first comparative example. The electric field structure is almost the same as that of the first comparative example. On the other hand, in the electric field structure in the fourth embodiment, a horizontal electric field is generated on the main substrate side between the electrodes, but the electric field runs in a direction that can no longer be called a horizontal electric field on the counter substrate side. The electric field strength in the vicinity of the counter substrate is weaker than the electric field strength in the first comparative example and the first embodiment of the present invention, and a weak electric field layer is formed. Further, when attention is paid to the electric field structure on the electrode, the electric field runs in the direction perpendicular to the substrate surface as in the first comparative example and the first embodiment, but the electric field strength is relatively weak. Is formed. Then, when the electric field strength between the electrodes in the vicinity of the counter substrate is compared with the electric field strength on the electrodes, the electric field strength between the electrodes is lower than the electric field strength on the electrodes. That is, the weak electric field layer in the present embodiment means that an electric field layer that is much weaker than the conventional electric field structure is formed focusing on the vicinity of the counter substrate. The electric field strength of this weak electric field layer is much weaker than the electric field strength near the electrode.

  Next, liquid crystal alignment, which is the third feature of the structure in this embodiment, will be described. Due to the electric field structure of the present invention described above, the liquid crystal molecules between the electrodes in the vicinity of the main substrate are twisted and deformed by a lateral electric field as in the conventional case. On the other hand, since the liquid crystal molecules in the weak electric field layer formed in the vicinity of the counter substrate have a lower electric field strength than before, they can move relatively freely independently of the electric field. As a result, the liquid crystal molecules in the weak electric field layer are twist-deformed following the change in the orientation of the liquid crystal molecules between the electrodes in the vicinity of the main substrate, rather than being aligned following the electric field. This is because it is more energetically stable to follow the alignment state of the surrounding liquid crystal molecules than to maintain the conventional alignment in a weak electric field or to align vertically according to a weak vertical electric field. Because it becomes. Note that the liquid crystal molecules on the electrode on the main substrate side rise somewhat due to the action of the electric field in the direction perpendicular to the substrate surface, but the electrode width itself may be small, and it is pushed by the surrounding twist orientation and stays in a narrow range. ing. Thereby, effective twist deformation of liquid crystal alignment is possible.

  Furthermore, compared with the first embodiment of the present invention described above, in the first embodiment described above, the liquid crystal molecules between the electrodes are twist-deformed by the electric field generated by the parallel electrode pair, and follow this deformation on the electrodes. The liquid crystal molecules are characterized in that their orientation changes in the same manner as the liquid crystal molecules between the electrodes against the electric field. On the other hand, in the fourth embodiment, the liquid crystal molecules between the electrodes on the substrate side having the parallel electrode pair are twist-deformed by the electric field generated by the parallel electrode pair, and the substrate on the inter-electrode is followed by this deformation. Liquid crystal molecules located away from the substrate are also twisted, and the liquid crystal molecules on the electrodes are also twisted following the twist deformation between these electrodes. In addition, it is characterized in that the orientation changes between the electrodes against the electric field direction. The liquid crystal alignment structure that is the third feature of this embodiment is realized by the electric field structure of the weak electric field layer that is the second feature of the present embodiment.

  Next, the electrode structure that realizes the second characteristic of the present embodiment, which is the weak electric field layer, and the operation thereof, that is, the first characteristic of the structure in the present embodiment will be described. As described above, the electrode structure of this embodiment is characterized in that the sum of the electrode width and the inter-electrode distance is equal to or less than the thickness of the liquid crystal layer. In order to realize a weak electric field layer, it is only necessary to confine a strong electric field layer having a larger electric field strength in the vicinity of the electrode. The details of the electric field distribution require an alignment simulation of liquid crystal molecules. For simplicity, as shown in the simulation result of FIG. 26, the strong electric field region is in the range of the height of W + S from the electrode in the thickness direction of the liquid crystal layer, that is, the electrode. It exists in the range of the sum of width and distance between electrodes. Accordingly, in order to form the weak electric field region, it is possible to set the thickness of the liquid crystal layer to be larger than the value of W + S. That is, d ≧ W + S. In the present embodiment, as described above, the electrode width is set to 0.5 μm, the distance between the electrodes is set to 2.5 μm, and the thickness of the liquid crystal layer is set to 4 μm, which satisfies the condition of d ≧ W + S.

  In this embodiment, most of the liquid crystal layer can be twisted by introducing a weak electric field layer. That is, the liquid crystal molecules between the electrodes on the substrate side having the parallel electrode pair are twist-deformed by the electric field generated by the parallel electrode pair, and the liquid crystal molecules located at a location away from the substrate between the electrodes following this deformation are also The liquid crystal molecules on the electrodes also twist and deform following the twist deformation between these electrodes, and in a place away from the substrate having the parallel electrode pair, not only on the electrodes but also between the electrodes in the electric field direction. On the contrary, the orientation changes. As a result, more liquid crystal molecules are aligned in the Y-axis direction than before, so that a higher transmittance than before can be realized.

  According to the liquid crystal display device of the present embodiment, a very high transmittance can be realized even if positive liquid crystal is used, due to the introduction of the weak electric field layer and the twist deformation mechanism of the liquid crystal layer. In addition, since the rising of the liquid crystal molecules in the Z-axis direction can be suppressed, the viewing angle characteristics can be improved.

  In the present embodiment, the liquid crystal molecules preferably have a twist elastic constant K22 of the liquid crystal molecules smaller than the bend elastic constant K33. Thereby, since the free energy at the time of twist deformation can be reduced, twist deformation of the entire liquid crystal layer becomes easier and the transmittance can be improved more efficiently.

  Further, although the liquid crystal molecules of the present embodiment have been described with respect to the positive type, the negative liquid crystal molecules described in the second or third embodiment of the present invention can also be used. In the positive type liquid crystal molecule, since the direction of refractive index anisotropy and the direction of dielectric anisotropy coincide, it is easy to improve the physical properties of the liquid crystal molecule in a preferable direction. As a result, it is possible to reduce the voltage and speed.

  Furthermore, in the present embodiment, a polarizing plate can be provided in the same manner as in the first embodiment of the present invention described above, but as in the first embodiment described above, the polarizing plate is not an essential configuration in the present invention. In one example, linearly polarized light such as laser light may be used on the incident side, and an observer who uses the display device may use polarized glasses.

  Furthermore, in the present embodiment, the case where the distance between the electrodes is equal to or greater than the electrode width has been described, but this is a very important point. When the distance between the electrodes is equal to or greater than the electrode width, twist deformation of the liquid crystal layer can be mainstream, and the transmittance can be improved. However, if the case where the electrode width is larger than the inter-electrode distance is considered, when attention is paid to the orientation change of the liquid crystal layer on the main substrate side, the twist deformation region between the electrodes becomes relatively small. As a result, the effect of twist deformation of the counter substrate side of the liquid crystal layer is reduced, and the twist deformation becomes difficult, and the rising of the liquid crystal molecules in the + Z-axis direction occurs, and the viewing angle characteristics are greatly deteriorated. It will be. In other words, it is important that the distance between the electrodes is not less than the electrode width.

  Furthermore, in the present embodiment, the case where the pixel electrode and the common electrode have the same electrode width has been described. However, the present invention is not limited to this, and may have different electrode widths. However, by setting the same electrode width, the electric field between the pixel electrode and the common electrode can be made more uniform, and display defects due to non-uniformity of the electric field can be reduced.

  Furthermore, in the present embodiment, as in the first embodiment of the present invention, it is not excluded that the pixel electrode and the common electrode are formed in different layers, but a gate electrode or a source for forming a thin film transistor. Alternatively, the pixel electrode or the common electrode may be formed using the drain electrode. In this case, even if the pixel electrode and the common electrode are formed in different layers, it is possible to cope without increasing the number of processes. In general, the gate electrode and the source or drain electrode are required to have low resistance, and thus are often made of an optically opaque metal. In general, a metal such as aluminum has higher workability than ITO, so that the electrode can be easily miniaturized. On the other hand, the display quality deteriorates due to the reflection of external light on the metal surface. However, since the present invention can use fine electrodes, it is possible to suppress the deterioration of the display quality. Note that the observer-side surface of the metal electrode may have a structure that reduces reflection of external light. In one example, a multilayer low reflection film may be formed on the metal electrode, or a black substance may be applied. Furthermore, in order to reduce regular reflection at the metal electrode, the electrode may be provided with a fine uneven structure.

  Furthermore, in the present invention, the main substrate on which the parallel electrode pair is formed and the counter substrate are described as the constituent requirements. However, the counter substrate is not necessarily a necessary constituent element. In one example, the upper portion of the liquid crystal layer may be a UV curable resin or the like. It may be supported by covering with. At this time, since the influence of anchoring from the counter substrate can be reduced, the liquid crystal layer has an advantage that alignment deformation is facilitated, and that the voltage can be lowered and the speed at the time of ON can be increased.

  Furthermore, in this embodiment, the main substrate is not limited to a glass substrate, and a silicon substrate or a quartz substrate can also be used. In particular, when a silicon substrate is used, the parallel electrode pair can be easily miniaturized. Operations and effects other than those described above in the fourth embodiment are the same as those in the first embodiment.

  Next, a liquid crystal display device according to a fifth embodiment of the present invention is described. FIG. 27 is a cross-sectional view showing the structure of the liquid crystal display device according to the present embodiment, and the alignment state of liquid crystal molecules when no voltage is applied between the pixel electrode and the common electrode, which are constituent elements, and FIG. It is sectional drawing which shows the electric field structure at the time of the voltage application of the liquid crystal display device of 5th Embodiment, and liquid crystal orientation, and is sectional drawing which showed especially the relationship between an electric field structure, liquid crystal orientation, and transmittance | permeability distribution by simulation.

  As shown in FIG. 27, the liquid crystal display device 14 shown in the fifth embodiment is common to the pixel electrode 33a having a width of 0.5 μm as compared with the liquid crystal display device 13 in the fourth embodiment of the present invention described above. Instead of the electrode 33b, a pixel electrode 34a and a common electrode 34b having a width of 0.2 μm are used. The distance between the pixel electrode 34a and the common electrode 34b, that is, the interelectrode distance is set to 0.9 μm. Further, a layer made of the same positive liquid crystal molecules 51 as that in the fourth embodiment is sandwiched between the main substrate 2a and the counter substrate 2b. The gap between the main substrate 2a and the counter substrate 2b, that is, the thickness of the layer made of the positive liquid crystal molecules 51 is set to 3.5 μm. As described above, the first feature of the structure according to the fifth embodiment is that the sum of the electrode width and the distance between the electrodes is not more than half of the thickness of the liquid crystal layer, that is, d ≧ 2 (W + S). In the point.

  FIG. 28 shows the relationship between the electric field structure and the liquid crystal alignment during voltage application of the liquid crystal display device according to the fifth embodiment. It is sectional drawing shown. A voltage that is a square wave of ± 5 V · 60 Hz is applied between the common electrode 34b and the pixel electrode 34a.

  As shown in FIG. 28, the second feature of the structure according to the fifth embodiment relates to the electric field structure, and is characterized by having a vertical electric field in the vicinity of the counter substrate between the electrodes. Further, the third feature of the structure in the fifth embodiment relates to a liquid crystal alignment structure, and due to this electric field structure, the liquid crystal molecules on the electrodes change their orientation in the same manner as the liquid crystal molecules between the electrodes. In the meantime, the director direction of the liquid crystal molecules has a region different from the electric field direction, and this region has more than half of the thickness of the liquid crystal layer. Other configurations in the present embodiment are the same as those in the fourth embodiment described above.

  Next, the operation of the liquid crystal display device according to the fifth embodiment configured as described above will be described. First, the electric field structure which is the second feature of the structure according to the present embodiment will be described. As described above, the electric field structure of the present invention is characterized by having a vertical electric field in the vicinity of the counter substrate between the electrodes. Here, paying attention to the transmittance simulation result shown in FIG. 28, the transmittance including on and between the electrodes is 85%, which is higher than that of the fourth embodiment of the present invention. Transmittance is achieved. As a result of intensive studies on this result, the inventors have invented an electric field structure that can realize higher transmittance than the above-described fourth embodiment. As described above, the electric field structure of the present invention is characterized in that it has a vertical electric field in the vicinity of the counter substrate between the electrodes, but this electric field structure is introduced when it has a comb electrode as in the electrode structure of the present invention. Thus, a vertical electric field can be generated not only on the electrodes but also between the electrodes in the vicinity of the counter substrate of the liquid crystal layer. Compared with the conventional IPS system and the first embodiment described above, a strong lateral electric field is generated in the vicinity of the counter substrate between the electrodes, and an electric field that cannot be clearly said to be a lateral electric field in the fourth embodiment described above. In contrast to this, in the present embodiment, as a result of introducing a vertical electric field in the vicinity of the counter substrate between the electrodes, the vertical electric field on the electrode that originally existed and equipotential lines are connected to each other on a plurality of electrodes. A significant difference is that straddling equipotential lines are generated, which is an important concept in the present embodiment. In the present embodiment, the weak electric field layer can be introduced near the center in the thickness direction of the liquid crystal layer by arranging the equipotential lines of the vertical electric field in this way. As a result, an alignment structure in which more than half of the counter substrate side of the liquid crystal layer is twist-deformed can be realized, so that higher transmittance can be achieved.

  That is, when the existence region of the weak electric field layer described in the fourth embodiment is compared with the present embodiment, the weak electric field layer is formed in the vicinity of the counter substrate of the liquid crystal layer in the fourth embodiment as shown in FIG. It had been. On the other hand, as shown in FIG. 28, in this embodiment, the weak electric field layer is formed on the counter substrate side from the vicinity of the center of the thickness of the liquid crystal layer. The weak electric field layer has an electric field in a direction substantially perpendicular to the substrate surface, and its strength is weaker than that of the fourth embodiment. That is, the weak electric field layer in this embodiment means that a vertical electric field layer that is much weaker than the conventional electric field structure is formed on the counter substrate side from the vicinity of the thickness center of the liquid crystal layer.

  Next, liquid crystal alignment, which is the third feature of the structure in this embodiment, will be described. The liquid crystal molecules between the electrodes in the vicinity of the main substrate are twist-deformed by a lateral electric field as in the conventional case, as in the fourth embodiment. This embodiment is characterized in that the liquid crystal molecules can move more freely because the electric field near the center of the thickness of the liquid crystal layer where anchoring by the alignment means of the liquid crystal layer is the weakest is weakened. . As a result, when the liquid crystal molecules between the electrodes in the vicinity of the main substrate are twist-deformed, the liquid crystal molecules in the half or more of the counter substrate side of the liquid crystal layer are similarly twist-deformed following the deformation. This is because it is more energetically stable to follow the alignment state of the surrounding liquid crystal molecules than to maintain the conventional alignment in a weak electric field or to align vertically according to a weak vertical electric field. Because it becomes. Note that the liquid crystal molecules on the electrode on the main substrate side rise somewhat due to the action of the electric field in the direction perpendicular to the substrate surface, but the electrode width itself may be small, and it is pushed by the surrounding twist orientation and stays in a narrow range. ing. Thereby, effective twist deformation of liquid crystal alignment is possible. The liquid crystal alignment structure which is the third feature of the present embodiment is realized by an electric field structure having a vertical electric field in the vicinity of the counter substrate between the electrodes which is the second feature of the present embodiment described above.

  Next, the electrode structure that realizes the second characteristic of the present embodiment, which is the weak electric field layer, and the operation thereof, that is, the first characteristic of the structure in the present embodiment will be described. As described above, the electrode structure of this embodiment is characterized in that the sum of the electrode width and the inter-electrode distance is not more than half of the thickness of the liquid crystal layer. As described above, the strong electric field layer having a relatively large electric field strength exists in the range of the height of W + S from the main substrate on which the electrodes are formed, that is, in the range of the sum of the electrode width and the interelectrode distance. Therefore, by setting the thickness of the liquid crystal layer to be larger than twice the value of W + S, a weak electric field layer can be generated in the liquid crystal layer on the + Z direction side from the vicinity of the center of the liquid crystal layer. That is, d ≧ 2 (W + S). In this embodiment, as described above, the electrode width is set to 0.2 μm, the distance between the electrodes is set to 0.9 μm, and the thickness of the liquid crystal layer is set to 3.5 μm, and the condition of d ≧ 2 (W + S) is satisfied. ing.

  In the present embodiment, twist deformation of the liquid crystal layer is made easier by introducing the weak electric field layer into a region more than half of the liquid crystal layer. In other words, the liquid crystal molecules between the electrodes on the substrate side having the parallel electrode pair are twist-deformed by the electric field generated by the parallel electrode pair, and the liquid crystal molecules located in the vicinity of the center of the liquid crystal layer between the electrodes are also twisted following the deformation. Further, the liquid crystal molecules on the electrodes are also deformed in a twisted manner following the twisted deformation between these electrodes. As a result, twist deformation is facilitated in a region of more than half of the liquid crystal layer, and in a place away from the substrate having the parallel electrode pair by more than half of the liquid crystal layer, the same applies to the opposite direction of the electric field not only on the electrodes but also between the electrodes. Twist changes. As a result, more liquid crystal molecules are aligned in the Y-axis direction than before, so that a higher transmittance can be realized than before.

  According to the liquid crystal display device of the present embodiment, a very high transmittance can be obtained even when positive liquid crystal is used due to the introduction of the weak electric field layer into more than half of the liquid crystal layer and the twist deformation mechanism of the liquid crystal layer. Can be realized. In addition, since the rising of the liquid crystal molecules in the Z-axis direction can be suppressed, the viewing angle characteristics can be improved.

  Note that the thickness of the liquid crystal layer in the present embodiment is preferably set within a range of about 5 μm, which is the thickness of a normal liquid crystal layer, in consideration of the deformation time of liquid crystal molecules. This is because when the thickness of the liquid crystal layer is increased, the anchoring action of the alignment means is weakened, so that the return of the liquid crystal alignment when the voltage is turned off becomes worse and the off response time becomes longer. That is, the sum of the electrode width and the distance between the electrodes is preferably set within 2.5 μm. Further, as described above, the electrode width W needs to be smaller than the inter-electrode distance S, and is preferably set in the range of W ≦ S / 4 as shown in the present embodiment. That is, the electrode width is preferably 0.5 μm or less.

  In addition, as shown in FIG. 29, it is preferable to provide a reverse rotation domain prevention structure 34c for preventing alignment deformation of liquid crystal molecules in an undesirable direction at the end portions of the pixel electrode and the common electrode in the present embodiment. In the fourth or fifth embodiment of the present invention, the introduction of this structure is particularly important. This is because the ratio of the transverse electric field is small in the method of the present invention compared to the normal IPS method, and the alignment deformation at the time of applying the electric field depends on the twist deformation of the liquid crystal molecules in the vicinity of the main substrate between the electrodes. This is because, when an undesirable orientation deformation is induced due to an abnormal electric field generated at the end portion of the comb-tooth electrode, the orientation deformation easily propagates, and a normal twist deformation becomes difficult. As an example of such a reverse rotation domain prevention structure, as shown in FIG. 29, there is a method of forming an electrode portion perpendicular to the rubbing direction at the end portions of the pixel electrode and the common electrode constituting the parallel electrode pair. .

  Furthermore, in the present embodiment, the alignment means is described as having an alignment film. However, the alignment means is not limited to this, and the unevenness of the parallel electrode pair is particularly limited when positive type liquid crystal is used. The structure can be used as an orientation means. This eliminates the need for alignment processing such as formation of an alignment film and rubbing, thereby reducing the cost of the apparatus. Furthermore, the parallel electrode pair may be slightly bent in the left-right direction, that is, the Y-axis direction in FIG. As a result, the initial alignment direction of the liquid crystal molecules becomes the extending direction of the parallel electrode pair, and the in-plane direction of the lateral electric field becomes a direction different from the Y-axis direction due to bending, so the angle between the liquid crystal molecules and the electric field is set to other than 90 °. Can be set. Thereby, the twist direction of the liquid crystal molecules when a voltage is applied can be made uniform in the plane. As the pitch of the microbending is increased, the angle of the liquid crystal molecules and the transverse electric field tends to be orthogonal, so that the pitch of the microbending is preferably set to be equal to or less than the pitch of the parallel electrode pair. Operations and effects other than those described above in the fifth embodiment are the same as those in the fourth embodiment described above.

  Next, a liquid crystal display device according to a sixth embodiment of the present invention is described. FIG. 30 is a cross-sectional view showing the structure of the liquid crystal display device according to this embodiment.

  As shown in FIG. 30, the liquid crystal display device 15 shown in the sixth embodiment is different from the fifth embodiment of the invention described above in that a reflecting plate 5 is formed on the main substrate 2a. . Note that a polarizing plate may be provided on the surface on the viewer side of the liquid crystal display device 15, but is omitted in FIG. 30. In one example, the absorption axis of the polarizing plate is arranged in accordance with the minor axis direction of the liquid crystal molecules. That is, the liquid crystal display device 15 in this embodiment operates as a normally white mode reflective display device. Operations and effects other than those described above in the sixth embodiment are the same as those in the fifth embodiment described above.

  Next, the operation of the liquid crystal display device according to the sixth embodiment configured as described above will be described. First, a case where no voltage is applied between the pixel electrode and the common electrode will be described. The linearly polarized light emitted from the polarizing plate toward the liquid crystal layer is incident on the liquid crystal layer. However, when no voltage is applied, the polarization direction of the linearly polarized light coincides with the major axis direction of the liquid crystal molecules. Reach the reflector in the state. The light reflected by the reflecting plate is emitted from the polarizing plate as it is without changing the polarization direction by the reflecting plate and the liquid crystal layer. That is, when no voltage is applied, white display is realized.

  As described in the fifth embodiment of the present invention, when a voltage is applied between the pixel electrode and the common electrode, the liquid crystal layer undergoes almost uniform twist deformation in the display surface, so that a uniform phase difference is obtained. A phase difference plate can be realized. In particular, when this phase difference is ¼ wavelength, the linearly polarized light incident on the liquid crystal layer from the polarizing plate becomes circularly polarized light and is emitted to the reflecting plate. Since the reflection plate rotates the polarization direction of the circularly polarized light by 180 degrees, the reflected light becomes circularly polarized light that rotates in the opposite direction, enters the liquid crystal layer, is converted into linearly polarized light that is orthogonal to the incident time, and the polarizing plate Head for. Since this light cannot be emitted from the polarizing plate, black display is realized by applying a voltage.

  As described in the first comparative example of the present invention, when the liquid crystal alignment in the liquid crystal layer is greatly different between the electrodes and between the electrodes when a voltage is applied, the liquid crystal layer cannot act as a uniform retardation plate. For this reason, particularly when used in the normally white mode, light leakage occurs during black display, and the contrast ratio of the display is greatly deteriorated.

  On the other hand, as described in this embodiment, when a uniform twist alignment is realized in the liquid crystal layer, a high contrast ratio can be realized.

  In addition, although the metal which has high reflectance with respect to light, such as aluminum and silver, can use the reflector in this embodiment, in order to prevent conduction | electrical_connection with a pixel electrode and a common electrode in this case, a pixel is used. It is preferable to provide an insulating layer between the electrode and the common electrode and the reflector.

  In addition, the liquid crystal display device in the present embodiment has been described as a reflective display device, but the present invention is not limited to this, and can be applied to a transmissive display device, and particularly to a transflective display device. It can be preferably used. In this transflective display device, considering that the pixel electrode is shared between the transmissive region and the reflective region, different voltages are applied to the common electrode in the transmissive region and the reflective region, and no retardation film is used, The area is normally black, and the reflection area is normally white. The optical operation of the transmissive region can achieve high transmittance as described in the fifth embodiment of the present invention, and the optical operation of the reflective region can display a high contrast reflective display as in this embodiment. Can be realized. Operations and effects other than those described above in the sixth embodiment are the same as those in the fifth embodiment described above.

  Next, a liquid crystal display device according to a seventh embodiment of the present invention is described. FIG. 31 is a cross-sectional view showing the structure of the liquid crystal display device according to this embodiment.

  As shown in FIG. 31, the liquid crystal display device 16 according to the seventh embodiment is a stereoscopic image display device provided with a lenticular lens 103. In the liquid crystal display device 16, pixel pairs as display units each including one left-eye pixel 104L and one right-eye pixel 104R are provided in a matrix. The lenticular lens 103 is a lens array in which a large number of cylindrical lenses 103a are arranged one-dimensionally, and the arrangement direction thereof is the direction in which the left-eye pixels 104L and the right-eye pixels 104R are repeatedly arranged, that is, the Y-axis direction in FIG. It has become. The extending direction of the cylindrical lens 103a, that is, the longitudinal direction is a direction orthogonal to the arrangement direction in the display surface, and is the X-axis direction in FIG. One pair of pixels in the Y-axis direction corresponds to one cylindrical lens 3a. The left-eye pixel 104L and the right-eye pixel 104R have the same structure as the pixel used in the liquid crystal display device according to the fifth embodiment of the present invention. The pixel electrode and the common electrode are repeatedly arranged in the Y-axis direction in FIG. Other configurations in the present embodiment are the same as those in the fifth embodiment described above.

  Next, the operation of the liquid crystal display device according to the seventh embodiment configured as described above will be described. First, the pixel enlargement operation of the lenticular lens 103 will be described. As shown in FIG. 31, the distance between the principal point of the lenticular lens 103, that is, the apex, and the pixel is H, the refractive index of the lenticular lens 103 is n, and the lens pitch is L. Also, let P be the pitch of each one of the left-eye pixel 104L or the right-eye pixel 104R. At this time, the arrangement pitch of the display pixels each including one left-eye pixel 104L and right-eye pixel 104R is 2P.

  The distance between the lenticular lens 103 and the observer is the optimum observation distance OD, and the period of the enlarged projection image of the pixel at this distance OD, that is, the left eye on a virtual plane that is separated from the lens by the distance OD and parallel to the lens. The period of the width of the projection image of the pixel for use 104L and the pixel for right eye 104R is assumed to be e. Further, WL is a distance from the center of the cylindrical lens 103a located at the center of the lenticular lens 103 to the center of the cylindrical lens 103a located at the end of the lenticular lens 103 in the X-axis direction, and is at the center of the display screen of the liquid crystal display device. Let WP be the distance between the center of the display pixel composed of the left-eye pixel 104L and the right-eye pixel 104R and the center of the display pixel located at the end of the display screen in the X-axis direction. Furthermore, the incident angle and the exit angle of light in the cylindrical lens 103a located at the center of the lenticular lens 103 are α and β, respectively, and the incident angle of light in the cylindrical lens 103a located at the end of the lenticular lens 103 in the X-axis direction and Let the outgoing angles be γ and δ, respectively. Furthermore, the difference between the distance WL and the distance WP is C, and the number of pixels included in the area of the distance WP is 2 m.

  Since the arrangement pitch L of the cylindrical lenses 103a and the arrangement pitch P of the pixels are related to each other, the other is determined according to one, but usually the lenticular lens is often designed according to the display panel. Therefore, the pixel arrangement pitch P is treated as a constant. Further, the refractive index n is determined by selecting the material of the lenticular lens 103a. On the other hand, the observation distance OD between the lens and the observer and the period e of the pixel enlarged projection image at the observation distance OD are set to desired values. These values are used to determine the distance H and lens pitch L between the vertex of the lens and the pixel. From Snell's law and geometric relationships, the following formulas 1 to 9 hold. Further, the following formulas 10 and 11 are established.

  In this embodiment, the distance H between the vertex of the lenticular lens and the pixel is set equal to the focal length f of the lenticular lens. Therefore, the following mathematical formula 16 is established, and when the curvature radius of the lens is r, the curvature radius r is obtained by the following mathematical formula 11.

  Here, the lateral magnification of the lenticular lens can be considered as a value obtained by dividing the period of the enlarged pixel projection image by the period of the pixel, that is, the pixel pitch, and is e / P times. For example, when a display panel having a pixel arrangement pitch P of 65 μm is used and the period e of the pixel enlarged projection image is set to 65 mm, the lenticular lens 103 has a lateral magnification of 1000 times. That is, the pixel electrode and the common electrode formed on the pixel are also magnified 1000 times and projected onto the observation surface. In one example, when a 5 μm width transmittance reduction region occurs in the pixel electrode or the common electrode portion, the observation surface is observed as a 5 mm width transmittance reduction region.

  As described in the first comparative example of the present invention, when the liquid crystal alignment in the liquid crystal layer is greatly different between the electrodes when the voltage is applied and a large transmittance distribution is generated in the X-axis direction, this transmittance distribution is generated. Is magnified by a lenticular lens and observed by an observer. In other words, when the observer changes the angle with the display device, bright and dark unevenness is superimposed on the display image and the observer feels that the quality of the display image is low.

  On the other hand, as described in this embodiment, when a uniform twist alignment is realized in the liquid crystal layer, the observer does not observe the transmittance distribution due to the electrode structure superimposed on the display image. , Display quality is not bad. That is, in the present invention, display quality can be improved.

  In the present embodiment, a two-viewpoint stereoscopic image display device having a left-eye pixel and a right-eye pixel has been described. However, the present invention is not limited to this, and an N-viewpoint (N is a natural number) method. The present invention can be similarly applied to the display device. In this case, in the definition of the distance WP described above, the number of pixels included in the area of the distance WP may be 2 × m, and may be handled as N × m. N may be 1, that is, the pixel and the lens may correspond one-to-one. In this case, the influence of a region that does not contribute to display such as a gate line or a data line can be reduced, and light use efficiency can be improved.

  Further, the present invention is not limited to the stereoscopic image display device, and can be similarly applied to any display device provided with a lenticular lens. In one example, the present invention can be similarly applied to a multi-image display device that displays a plurality of planar images in different directions.

  Further, the image separation means of the present invention is not limited to a lenticular lens, but a fly-eye lens in which lens elements are two-dimensionally arranged, a parallax barrier in which slits are one-dimensionally arranged, and a parallax barrier in which pinholes are two-dimensionally arranged. Can be applied as well. In other words, this embodiment can be suitably used in the case where an optical means for enlarging and displaying pixels is provided, and high image quality is possible.

  Further, the present invention can be similarly applied not only to a transmissive liquid crystal display device but also to a reflective liquid crystal display device, a transflective liquid crystal display device, and a slightly reflective liquid crystal display device.

  Furthermore, it is desirable that the pixel electrode and the common electrode in the present embodiment are formed using a transparent conductor such as ITO, but an improvement effect can also be obtained when a metal is used. This is because the in-plane uniformity in the transmittance of the liquid crystal layer can be improved by improving the liquid crystal alignment around the metal electrode. Operations and effects other than those described above in the seventh embodiment are the same as those in the fifth embodiment described above.

  Next, a liquid crystal display device according to an eighth embodiment of the present invention is described. FIG. 32 is a cross-sectional view showing the structure of the liquid crystal display device according to the present embodiment, and FIG. 33 is a perspective view showing a louver which is a component and a light beam direction restricting element.

  As shown in FIG. 32, the liquid crystal display device 17 according to the eighth embodiment of the present invention has a light beam direction restriction on the + Z direction side of the liquid crystal display device 14 as compared with the liquid crystal display device 14 in the fifth embodiment described above. It is characterized by having a louver 212 as an element.

  As shown in FIG. 33, in the louver 212, transparent regions 212a that transmit light and absorption regions 212b that absorb light are alternately arranged in a direction parallel to the louver surface. The direction in which the transparent areas and the absorption areas are alternately arranged is set in the Y-axis direction in FIGS. 32 and 33. Other configurations in the present embodiment are the same as those in the fifth embodiment described above.

  In the present embodiment, the light beam incident on the louver 212 has an action of absorbing and removing a component having a large angle from the normal line direction with respect to the emission surface, so that the directivity of the light beam emitted from the liquid crystal display device 17 is improved. be able to. Thereby, it is possible to prevent a peep from an oblique direction, and to exhibit an effect of preventing leakage of secret information.

  Here, as described in the first comparative example of the present invention, when the liquid crystal alignment in the liquid crystal layer is greatly different between the electrodes and between the electrodes when a voltage is applied, and a large transmittance distribution occurs in the X-axis direction, The transmittance distribution and the absorption region 212b of the louver 212 interfere with each other, and the observer observes that the display quality of the image is deteriorated.

  On the other hand, as described in this embodiment, when a uniform twist alignment is realized in the liquid crystal layer, deterioration in image quality due to interference between the transmittance distribution due to the electrode structure and the absorption region of the louver is prevented. The observer does not feel that the display quality is low. That is, according to the present invention, it is possible to improve the display quality when the louver is used.

  In addition, although the louver which is a light direction restricting element in the present invention has been described as the direction in which the transparent region and the absorption region are alternately arranged is the Y-axis direction, the louver may be rotationally arranged in the XY plane. .

  In the present embodiment, an example of a louver which is a light beam direction restricting element has been described. However, the present invention is not limited to this, and the present invention is similarly applied to an optical element for controlling the directivity of emitted light. can do. As such an example, a prism sheet constituting a backlight can be cited, and the present invention can be similarly applied. Operations and effects other than those described above in the eighth embodiment are the same as those in the fifth embodiment described above.

  In addition, although each above-mentioned embodiment may each be used independently, it is also possible to use it combining suitably.

  The present invention is suitable for display devices of portable terminal devices such as mobile phones, PDAs, game machines, digital cameras, video cameras and video players, and display devices of terminal devices such as notebook personal computers, cash dispensers, and vending machines. Can be used.

It is sectional drawing which shows the state at the time of the voltage application of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the orientation state of a liquid crystal molecule when a voltage is not applied between the pixel electrode which is a component of this embodiment, and a common electrode. It is a perspective view which shows the terminal device carrying the liquid crystal display device which concerns on this embodiment. It is a microscope picture for showing the transmittance | permeability distribution of a liquid crystal display device when a voltage is not applied between a common electrode and a pixel electrode. It is a microscope picture for showing the transmittance distribution of a liquid crystal display device at the time of applying a square wave voltage of ± 5V and 60Hz between a common electrode and a pixel electrode. It is the graph which measured the voltage-transmittance characteristic in the 1 micrometer diameter area | region of the center part between electrodes. It is the graph which measured the voltage-transmittance characteristic in the 1-micrometer-diameter area | region on an electrode. It is the result of having simulated the liquid crystal alignment of this embodiment, electric field distribution, and transmittance | permeability distribution. It is the enlarged view which showed the liquid crystal orientation on the electrode in the simulation result of FIG. It is the graph which measured the voltage-transmittance characteristic in the area | region with a diameter of 100 micrometers including on between electrodes and between electrodes. It is sectional drawing which shows the state at the time of the voltage application of the liquid crystal display device which concerns on the 1st comparative example of this invention. It is a microscope picture for showing the transmittance distribution of a liquid crystal display device at the time of applying a square wave voltage of ± 5V and 60Hz between a common electrode and a pixel electrode. It is the graph which measured the voltage-transmittance characteristic in the 1 micrometer diameter area | region of the center part between electrodes. It is the graph which measured the voltage-transmittance characteristic in the 1-micrometer-diameter area | region on an electrode. It is the result of having simulated the liquid crystal alignment of this embodiment, electric field distribution, and transmittance | permeability distribution. FIG. 16 is an enlarged view showing liquid crystal alignment on the electrode in the simulation result of FIG. 15. It is the graph which measured the voltage-transmittance characteristic in the area | region with a diameter of 100 micrometers including on between electrodes and between electrodes. It is the graph which measured the voltage-transmittance characteristic in the area | region with a diameter of 100 micrometers including on between the electrodes about the liquid crystal display device which concerns on the 2nd comparative example of this invention. It is sectional drawing which shows the state at the time of the voltage application of the liquid crystal display device which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the orientation state of a liquid crystal molecule when a voltage is not applied between the pixel electrode which is a component of this embodiment, and a common electrode. It is the graph which measured the voltage-transmittance characteristic in the area | region with a diameter of 100 micrometers including on between electrodes and between electrodes. It is the result of having simulated the liquid crystal alignment of this embodiment, electric field distribution, and transmittance | permeability distribution. It is the enlarged view which showed the liquid crystal orientation on the electrode in the simulation result of FIG. It is the graph which measured the voltage-transmittance characteristic in the area | region with a diameter of 100 micrometers including on between the electrodes about the liquid crystal display device which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the liquid crystal display device which concerns on the 4th Embodiment of this invention, and the orientation state of a liquid crystal molecule when a voltage is not applied between the pixel electrode which is the component, and a common electrode. It is sectional drawing which shows the electric field structure and liquid crystal orientation at the time of the voltage application of the liquid crystal display device which concerns on this embodiment, and is sectional drawing which showed especially the relationship between an electric field structure, liquid crystal orientation, and transmittance | permeability distribution by simulation. It is sectional drawing which shows the structure of the liquid crystal display device which concerns on the 5th Embodiment of this invention, and the orientation state of a liquid crystal molecule when a voltage is not applied between the pixel electrode and common electrode which are the components. It is sectional drawing which shows the electric field structure and liquid crystal orientation at the time of the voltage application of the liquid crystal display device which concerns on this embodiment, and is sectional drawing which showed especially the relationship between an electric field structure, liquid crystal orientation, and transmittance | permeability distribution by simulation. In the liquid crystal display device according to the present embodiment, it is a top view showing a reverse rotation domain prevention structure. It is sectional drawing which shows the liquid crystal display device which concerns on the 6th Embodiment of this invention. It is sectional drawing which shows the liquid crystal display device which concerns on the 7th Embodiment of this invention. It is sectional drawing which shows the liquid crystal display device which concerns on the 8th Embodiment of this invention. In the liquid crystal display device which concerns on this embodiment, it is a perspective view which shows the louver which is the component and is a light beam direction control element. FIG. 11 is a cross-sectional view schematically showing an IPS liquid crystal panel used in a conventional first liquid crystal display device described in Patent Document 1. It is sectional drawing which shows typically the liquid crystal panel used for the 2nd conventional liquid crystal display device described in patent document 1, and is a liquid crystal panel of a FFS system.

Explanation of symbols

1, 11, 12, 13, 14, 15, 16, 17; liquid crystal display device 2a; main substrate 2b; counter substrate 3a, 31a, 32a, 33a, 34a; pixel electrode 3b, 31b, 32b, 33b, 34b; common Electrode 34c; Reverse rotation domain prevention structure 4; Alignment film 41; Rubbing direction 5; Reflector 9; Mobile terminal device 51; Positive liquid crystal molecule 52; Negative liquid crystal molecule 103; Lenticular lens 103a; Cylindrical lens 104L; Pixel 104R; Right eye pixel 151; Right eye 152; Left eye 212; Louver 212a; Transparent region 212b; Absorption region 1200, 1201; Substrate 1202; Liquid crystal molecules 1203, 1204; Electrode 1300; Liquid crystal panel 2200, 2201; Liquid crystal molecules 2203, 2204; electrode 2205; insulating layer 2300; The liquid crystal panel

Claims (16)

A substrate having at least a pair of parallel electrodes, and a liquid crystal layer disposed on the substrate,
The total value of the width and interval of the electrodes constituting the parallel electrode pair is less than or equal to half the thickness of the liquid crystal layer;
The liquid crystal molecules of the liquid crystal layer are driven by the electric field generated by the parallel electrode pair, the electric field on the electrodes has a vertical electric field component larger than the horizontal electric field component, and the electric field between the electrodes is longer than the horizontal electric field component. field component is small, the director direction of the liquid crystal molecules in the region away from the vicinity of the substrate between the electrodes and on the electrodes, respectively, have a different area than the electric field direction between the electrodes and on the electrodes, this region Is a horizontal electric field in which there is an electric field region in which the electric field direction between the electrodes is perpendicular to the substrate surface on the opposite substrate side from the central region in the thickness direction of the liquid crystal layer. In the drive type liquid crystal display device,
By increasing the lateral electric field on the electrodes by making the electrode width of the parallel electrode pair smaller than the thickness of the liquid crystal layer, the liquid crystal molecules on the electrodes change their orientation in the same manner as the liquid crystal molecules between the electrodes. Composed and
Occurs in the parallel electrode pair by reducing the twist deformation attenuation of the liquid crystal molecules due to the transverse electric field on the electrodes by making the twist elastic constants of the liquid crystal molecules smaller than the bend elastic constants of the liquid crystal molecules. When the liquid crystal molecules in the vicinity of the substrate between the electrodes are twist-deformed by an electric field, the liquid crystal molecules on the electrodes follow the twist deformation and between the electrodes from the vicinity of the substrate in the thickness direction of the liquid crystal layer. The liquid crystal molecules in a remote area are configured to undergo the same twist deformation as the liquid crystal molecules between the electrodes,
The parallel electrode pairs are formed to extend in parallel to a pixel separation direction that separates adjacent pixels in the horizontal direction and are arranged in a direction perpendicular to the pixel separation direction;
The electrode arrangement direction of said parallel electrode pair, have a pixel enlarging means for enlarging the image of each pixel optically with the liquid crystal layer,
An electrode portion perpendicular to the rubbing direction is formed as a reverse rotation domain prevention structure at the end portion of the pixel electrode and the common electrode constituting the parallel electrode pair.
A liquid crystal display device characterized by the above.   2. The liquid crystal display device according to claim 1, wherein a distance between electrodes constituting the parallel electrode pair is equal to or greater than a width of the electrodes.   3. The liquid crystal display device according to claim 1, wherein the liquid crystal molecules of the liquid crystal layer have positive dielectric anisotropy.   In the liquid crystal layer on the electrodes constituting the parallel electrode pair, there are liquid crystal molecules in which the director direction of the liquid crystal molecules when an electric field is generated in the parallel electrode pair is the arrangement direction of the electrodes constituting the parallel electrode pair The liquid crystal display device according to claim 3.   3. The liquid crystal display device according to claim 1, wherein the liquid crystal molecules of the liquid crystal layer have a negative dielectric anisotropy.   In the liquid crystal layer on the electrodes constituting the parallel electrode pair, there exists liquid crystal molecules in which the director direction of the liquid crystal molecules when an electric field is generated in the parallel electrode pair is the longitudinal direction of the electrodes constituting the parallel electrode pair The liquid crystal display device according to claim 5. The liquid crystal display device according to any one of claims 1 to 6, characterized in that the parallel electrode pair is formed in the same layer. The parallel electrode pair of liquid crystal layer side, and the liquid crystal display device according to any one of claims 1 to 7, characterized in that it has an overcoat layer between the electrodes constituting the parallel electrode pair. The liquid crystal display device according to any one of claims 1 to 7, characterized in that it has a flattening layer between the electrodes constituting the parallel electrode pair. The parallel pair of electrodes a liquid crystal display device according to claim 1 to 9, characterized in that they are composed of a transparent conductor. The parallel pair of electrodes a liquid crystal display device according to claim 1 to 9, characterized in that it is made of metal. The liquid crystal display device according to claim 11 , further comprising reflection reducing means on a surface of the parallel electrode pair on the liquid crystal layer side. The liquid crystal display device according to claim 1 to 12, wherein the electrode width of the parallel electrode pair is 1μm or less. The liquid crystal display device according to any one of claims 1 to 13, characterized in that operate in the normally white mode. Terminal device comprising the liquid crystal display device according to any one of claims 1 to 14. The terminal device according to claim 15 , wherein the terminal device is a mobile phone, a personal information terminal, a game machine, a digital camera, a video camera, a video player, a notebook personal computer, a cash dispenser, or a vending machine.

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